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Khan Academy - Geometry 1-48

Euclid as the father of geometry | Introduction to Euclidean geometry | Geometry | Khan Academy
Euclid as the father of geometry | Introduction to Euclidean geometry | Geometry | Khan AcademyWe don't normally delve too far into history when talking about math, but sometimes it's important to have perspective about how some of our math conce…
- 28 Feb 12, 10:18pm -
Basic geometry: language and labels | Introduction to Euclidean geometry | Geometry | Khan Academy
Basic geometry: language and labels | Introduction to Euclidean geometry | Geometry | Khan AcademyBefore learning any new concept (mathematical or otherwise), it's important we learn and use a common language and label concepts consistently.Wat…
- 28 Feb 12, 10:16pm -
Area of Koch snowflake (part 2) - advanced | Perimeter, area, and volume | Geometry | Khan Academy
Area of Koch snowflake (part 2) - advanced | Perimeter, area, and volume | Geometry | Khan AcademySumming an infinite geometric series to finally find the finite area of a Koch SnowflakeWatch the next lesson: https://www.khanacademy.org/math/ge…
- 5 Oct 11, 6:27pm -
Area of Koch snowflake (part 1) - advanced | Perimeter, area, and volume | Geometry | Khan Academy
Area of Koch snowflake (part 1) - advanced | Perimeter, area, and volume | Geometry | Khan AcademyStarting to figure out the area of a Koch Snowflake (which has an infinite perimeter)Watch the next lesson: https://www.khanacademy.org/math/geome…
- 5 Oct 11, 6:26pm -
Area of an equilateral triangle | Perimeter, area, and volume | Geometry | Khan Academy
Area of an equilateral triangle | Perimeter, area, and volume | Geometry | Khan AcademyFinding the formula for the area of an equilateral triangle with side sWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/perime…
- 5 Oct 11, 6:25pm -
Finding area using similarity and congruence | Similarity | Geometry | Khan Academy
Finding area using similarity and congruence | Similarity | Geometry | Khan AcademyExample of using similarity and congruence to find the area of a trianglePractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org…
- 4 Oct 11, 5:47pm -
Similar triangle example problems | Similarity | Geometry | Khan Academy
Similar triangle example problems | Similarity | Geometry | Khan AcademyMultiple examples looking for similarity of trianglesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/similarity/trian…
- 4 Oct 11, 12:27am -
Similarity example where same side plays different roles | Similarity | Geometry | Khan Academy
Similarity example where same side plays different roles | Similarity | Geometry | Khan AcademyThe same side not corresponding to itself in two similar trianglesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacadem…
- 3 Oct 11, 4:00pm -
Challenging similarity problem | Similarity | Geometry | Khan Academy
Challenging similarity problem | Similarity | Geometry | Khan AcademyInteresting similarity problem where we don't have a lot of information to work withPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/ma…
- 3 Oct 11, 3:30pm -
Sum of interior angles of a polygon | Angles and intersecting lines | Geometry | Khan Academy
Sum of interior angles of a polygon | Angles and intersecting lines | Geometry | Khan AcademyShowing a generalized way to find the sum of the interior angles of any polygonPractice this lesson yourself on KhanAcademy.org right now: https://www…
- 2 Oct 11, 2:17pm -
Similarity example problems | Similarity | Geometry | Khan Academy
Similarity example problems | Similarity | Geometry | Khan AcademyTwo example problems involving similarityPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/similarity/triangle_similarlity/e/…
- 2 Oct 11, 12:01am -
Similarity postulates | Similarity | Geometry | Khan Academy
Similarity postulates | Similarity | Geometry | Khan AcademyThinking about what we need to know to determine whether two triangles are similarPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry…
- 1 Oct 11, 11:59pm -
Similar triangle basics | Similarity | Geometry | Khan Academy
Similar triangle basics | Similarity | Geometry | Khan AcademyIntroduction to what it means for triangles to be similarPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/similarity/triangle_si…
- 1 Oct 11, 11:29pm -
Challenging perimeter problem | Perimeter, area, and volume | Geometry | Khan Academy
Challenging perimeter problem | Perimeter, area, and volume | Geometry | Khan AcademyPerimeter of rectangle covered by 9 non-overlapping squares. From 2000 American Invitational Math ExamWatch the next lesson: https://www.khanacademy.org/math/g…
- 30 Sep 11, 5:28pm -
Koch snowflake fractal | Perimeter, area, and volume | Geometry | Khan Academy
Koch snowflake fractal | Perimeter, area, and volume | Geometry | Khan AcademyA shape that has an infinite perimeter but finite areaWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/koch_snowflake/v/area-of-an-equi…
- 30 Sep 11, 4:50pm -
Interesting perimeter and area problems | Perimeter, area, and volume | Geometry | Khan Academy
Interesting perimeter and area problems | Perimeter, area, and volume | Geometry | Khan AcademyThree example problems involving perimeter and areaWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/perimeter_area_tut…
- 30 Sep 11, 4:01pm -
Triangle area proofs | Perimeter, area, and volume | Geometry | Khan Academy
Triangle area proofs | Perimeter, area, and volume | Geometry | Khan AcademyProving that the area of any triangle is 1/2 b x hPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/basic-geometry/…
- 30 Sep 11, 3:15pm -
Perimeter and area: the basics | Perimeter, area, and volume | Geometry | Khan Academy
Perimeter and area: the basics | Perimeter, area, and volume | Geometry | Khan AcademyGreat geometry primer on perimeter and area. Listen carefully. Sal explains the concepts so you'll understand them.Practice this lesson yourself on KhanAcadem…
- 30 Sep 11, 2:29pm -
Figuring out all the angles for congruent triangles example | Congruence | Geometry | Khan Academy
Figuring out all the angles for congruent triangles example | Congruence | Geometry | Khan AcademyAnother example of using congruency to figure out a bunch of anglesWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-tria…
- 29 Sep 11, 9:26pm -
Example involving an isosceles triangle and parallel lines | Congruence | Geometry | Khan Academy
Example involving an isosceles triangle and parallel lines | Congruence | Geometry | Khan AcademyIntegrating what we know about isosceles triangles and parallel linesWatch the next lesson: https://www.khanacademy.org/math/geometry/similarity/si…
- 29 Sep 11, 8:54pm -
Another isosceles example problem | Congruence | Geometry | Khan Academy
Another isosceles example problem | Congruence | Geometry | Khan AcademyPossible angles for an isosceles triangleWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triangles/isoscleles_equil/v/example-involving-an-isosce…
- 29 Sep 11, 8:54pm -
Equilateral and isosceles example problems | Congruence | Geometry | Khan Academy
Equilateral and isosceles example problems | Congruence | Geometry | Khan AcademyThree example problems involving isosceles and equilateral triangles. 2 from Art of Problem Solving (by Richard Rusczyk) bookPractice this lesson yourself on KhanA…
- 29 Sep 11, 4:02pm -
Equilateral triangle sides and angles congruent | Congruence | Geometry | Khan Academy
Equilateral triangle sides and angles congruent | Congruence | Geometry | Khan AcademyShowing that all of the angles of an equilateral triangle are 60 degreesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.o…
- 29 Sep 11, 3:36pm -
Congruent legs and base angles of isosceles triangles | Congruence | Geometry | Khan Academy
Congruent legs and base angles of isosceles triangles | Congruence | Geometry | Khan AcademyShowing that congruent legs imply equal base angles and vice versaPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.o…
- 29 Sep 11, 3:09pm -
Congruent triangle example 2 | Congruence | Geometry | Khan Academy
Congruent triangle example 2 | Congruence | Geometry | Khan AcademyShowing that segments have the same lengthWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triangles/cong_triangle/v/figuring-out-all-the-angles-for-co…
- 27 Sep 11, 4:10am -
Congruent triangle proof example | Congruence | Geometry | Khan Academy
Congruent triangle proof example | Congruence | Geometry | Khan AcademyProving that a point is the midpoint via triangle congruencyWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triangles/cong_triangle/v/congruent-tr…
- 27 Sep 11, 4:10am -
More on why SSA is not a postulate | Congruence | Geometry | Khan Academy
More on why SSA is not a postulate | Congruence | Geometry | Khan AcademySSA special cases including RSHWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triangles/cong_triangle/v/perpendicular-radius-bisects-chord?utm_…
- 26 Sep 11, 10:54pm -
Finding congruent triangles | Congruence | Geometry | Khan Academy
Finding congruent triangles | Congruence | Geometry | Khan AcademyUsing the SSS, ASA, SAS, and AAS postulates to find congruent trianglesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/cong…
- 26 Sep 11, 10:16pm -
Sum of the exterior angles of convex polygon | Geometry | Khan Academy
Sum of the exterior angles of convex polygon | Geometry | Khan AcademyMore elegant way to find the sum of the exterior angles of a convex polygonWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/o…
- 26 Sep 11, 4:48am -
Two column proof showing segments are perpendicular | Congruence | Geometry | Khan Academy
Two column proof showing segments are perpendicular | Congruence | Geometry | Khan AcademyUsing triangle congruency postulates to show that two intersecting segments are perpendicularWatch the next lesson: https://www.khanacademy.org/math/geome…
- 23 Sep 11, 7:14pm -
Other triangle congruence postulates | Congruence | Geometry | Khan Academy
Other triangle congruence postulates | Congruence | Geometry | Khan AcademySSS, SAS, ASA and AAS postulates for congruent triangles. Showing AAA is only good for similarity and SSA is good for neitherWatch the next lesson: https://www.khanacade…
- 23 Sep 11, 6:31pm -
SSS to show a radius is perpendicular to a chord that it bisects | Geometry | Khan Academy
SSS to show a radius is perpendicular to a chord that it bisects | Geometry | Khan AcademyMore on the difference between a theorem and axiom. Proving a cool result using SSSWatch the next lesson: https://www.khanacademy.org/math/geometry/congru…
- 23 Sep 11, 4:19pm -
Congruent triangles and SSS | Congruence | Geometry | Khan Academy
Congruent triangles and SSS | Congruence | Geometry | Khan AcademyWhat it means for triangles to be congruentWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triangles/cong_triangle/v/sss-to-show-a-radius-is-perpendicu…
- 23 Sep 11, 4:18pm -
Finding more angles | Angles and intersecting lines | Geometry | Khan Academy
Finding more angles | Angles and intersecting lines | Geometry | Khan AcademyExample of angle hunting!Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/triang…
- 22 Sep 11, 7:11pm -
Proof: Corresponding angle equivalence implies parallel lines | Geometry | Khan Academy
Proof: Corresponding angle equivalence implies parallel lines | Geometry | Khan AcademyProof by contradiction that corresponding angle equivalence implies parallel linesWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-a…
- 22 Sep 11, 7:11pm -
Challenging triangle angle problem | Angles and intersecting lines | Geometry | Khan Academy
Challenging triangle angle problem | Angles and intersecting lines | Geometry | Khan AcademyInteresting problem finding the sums of particular exterior angles of an irregular pentagonWatch the next lesson: https://www.khanacademy.org/math/geome…
- 22 Sep 11, 6:45pm -
Triangle angle example 3 | Angles and intersecting lines | Geometry | Khan Academy
Triangle angle example 3 | Angles and intersecting lines | Geometry | Khan AcademyMultiple ways to solve for the angles of multiple trianglesWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/trian…
- 22 Sep 11, 6:43pm -
Triangle angle example 2 | Angles and intersecting lines | Geometry | Khan Academy
Triangle angle example 2 | Angles and intersecting lines | Geometry | Khan AcademyAnother example finding angles in trianglesWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/triang_prop_tut/v/tri…
- 22 Sep 11, 5:04pm -
Triangle angle example 1 | Angles and intersecting lines | Geometry | Khan Academy
Triangle angle example 1 | Angles and intersecting lines | Geometry | Khan AcademyFiguring out angles in a triangle. A little about exterior angles being the sum of the remote interior anglesWatch the next lesson: https://www.khanacademy.org/ma…
- 22 Sep 11, 4:11pm -
Proof - Sum of Measures of Angles in a Triangle are 180
Proof - Sum of Measures of Angles in a Triangle are 180Proof that the sum of the measures of the angles in a triangle are 180From:Khan AcademyViews:150042 417ratingsTime:06:31More inEducation
- 22 Sep 11, 3:16pm -
Measuring angles using a protractor | Angles and intersecting lines | Geometry | Khan Academy
Measuring angles using a protractor | Angles and intersecting lines | Geometry | Khan AcademyLet's use our virtual protractor to measure some angles together, shall we?Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-an…
- 22 Sep 11, 12:20am -
Angles formed by parallel lines and transversals | Geometry | Khan Academy
Angles formed by parallel lines and transversals | Geometry | Khan AcademyParallel lines, transversal lines, corresponding anglesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/parallel-and…
- 21 Sep 11, 11:24pm -
Proof: Vertical angles are equal | Angles and intersecting lines | Geometry | Khan Academy
Proof: Vertical angles are equal | Angles and intersecting lines | Geometry | Khan AcademyProving that vertical angles are equalPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/parallel-and-…
- 21 Sep 11, 7:17pm -
Introduction to vertical angles | Angles and intersecting lines | Geometry | Khan Academy
Introduction to vertical angles | Angles and intersecting lines | Geometry | Khan AcademyBy using our knowledge of supplementary, adjacent, and vertical angles, we can solve problems involving the intersection of two lines, including this one!P…
- 21 Sep 11, 7:15pm -
Complementary and supplementary angles | Angles and intersecting lines | Geometry | Khan Academy
Complementary and supplementary angles | Angles and intersecting lines | Geometry | Khan AcademyLet's add some tools to our geometry tool belt. Here's a thorough explanation of complementary and supplementary angles, as well as definitions of adj…
- 21 Sep 11, 4:29pm -
Measuring angles in degrees | Angles and intersecting lines | Geometry | Khan Academy
Measuring angles in degrees | Angles and intersecting lines | Geometry | Khan AcademyLet's come up with an exact way to measure an angle using a protractor. We'll also learn about acute angles. Not to be confused with augly angles :)Watch the n…
- 21 Sep 11, 3:07pm -
Angle basics | Angles and intersecting lines | Geometry | Khan Academy
Angle basics | Angles and intersecting lines | Geometry | Khan AcademyThe naming of an angle is related to the line segments that create it. We'll also learn about the angle's vertex. Come on. Let's do this.Watch the next lesson: https://www.kh…
- 21 Sep 11, 2:33pm -
Language and notation of the circle | Introduction to Euclidean geometry | Geometry | Khan Academy
Language and notation of the circle | Introduction to Euclidean geometry | Geometry | Khan AcademyFormal definition of a circle. Tangent and secant lines. Diameters and radii. major and minor arcsWatch the next lesson: https://www.khanacademy.o…
- 20 Sep 11, 9:19pm -
Intro to lines, line segments, and rays | Geometry | Khan Academy
Intro to lines, line segments, and rays | Geometry | Khan AcademyLet's get familiar with the difference between lines, line segments, and rays. Hint: a ray is somewhere between a line and a line segment!Practice this lesson yourself on KhanAcad…
- 23 Aug 11, 5:27pm -
More angle measurements using a protractor | Angles and intersecting lines | Geometry | Khan Academy
More angle measurements using a protractor | Angles and intersecting lines | Geometry | Khan AcademyWe're practicing measuring angles using the virtual protractor. Do this a few times with us and you'll use a real protractor like a pro!Practice…
- 23 Aug 11, 5:25pm -

Khan Academy - Geometry 49-96

Proving that the centroid is 2-3rds along the median | Geometry | Khan Academy
Proving that the centroid is 2-3rds along the median | Geometry | Khan AcademyShowing that the centroid divides each median into segments with a 2:1 ratio (or that the centroid is 2/3 along the median)Watch the next lesson: https://www.khanacad…
- 17 Oct 11, 4:41pm -
Exploring medial triangles | Special properties and parts of triangles | Geometry | Khan Academy
Exploring medial triangles | Special properties and parts of triangles | Geometry | Khan AcademyWhat a medial triangle is and its propertiesWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/medians_centroids/v…
- 13 Oct 11, 11:28pm -
Medians divide into smaller triangles of equal area | Geometry | Khan Academy
Medians divide into smaller triangles of equal area | Geometry | Khan AcademyShowing that the three medians of a triangle divide it into six smaller triangles of equal area. Brief discussion of the centroid as wellWatch the next lesson: https:/…
- 13 Oct 11, 4:48pm -
Angle bisector theorem examples | Geometry | Khan Academy
Angle bisector theorem examples | Geometry | Khan AcademyUsing the angle bisector theorem to solve for sides of a trianglePractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/triangle-properties…
- 13 Oct 11, 4:47pm -
Inradius, perimeter, and area | Special properties and parts of triangles | Geometry | Khan Academy
Inradius, perimeter, and area | Special properties and parts of triangles | Geometry | Khan AcademyShowing that area is equal to inradius times semiperimeterWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/an…
- 13 Oct 11, 3:54pm -
Angle bisector theorem proof | Special properties and parts of triangles | Geometry | Khan Academy
Angle bisector theorem proof | Special properties and parts of triangles | Geometry | Khan AcademyWhat the angle bisector theorem is and its proofWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/angle_bisecto…
- 12 Oct 11, 11:53pm -
Incenter and incircles of a triangle | Geometry | Khan Academy
Incenter and incircles of a triangle | Geometry | Khan AcademyUsing angle bisectors to find the incenter and incircle of a triangleWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/angle_bisectors/v/inradius-p…
- 12 Oct 11, 11:52pm -
Point-line distance and angle bisectors | Geometry | Khan Academy
Point-line distance and angle bisectors | Geometry | Khan AcademyThinking about the distance between a point and a line. Proof that a point on an angle bisector is equidistant to the sides of the angle and a point equidistant to the sides is on a…
- 12 Oct 11, 4:59pm -
Three points defining a circle | Special properties and parts of triangles | Geometry | Khan Academy
Three points defining a circle | Special properties and parts of triangles | Geometry | Khan AcademyThree points uniquely define a circle. The center of a circle is the circumcenter of any triangle the circle is circumscribed about.Watch the ne…
- 12 Oct 11, 4:16pm -
Circumcenter of a right triangle | Geometry | Khan Academy
Circumcenter of a right triangle | Geometry | Khan AcademyShowing that the midpoint of the hypotenuse is the circumcenterWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/perpendicular_bisectors/v/three-points…
- 7 Oct 11, 7:27pm -
Circumcenter of a triangle | Special properties and parts of triangles | Geometry | Khan Academy
Circumcenter of a triangle | Special properties and parts of triangles | Geometry | Khan AcademyMultiple proofs showing that a point is on a perpendicular bisector of a segment if and only if it is equidistant from the endpoints. Using this to es…
- 7 Oct 11, 6:21pm -
Perpendicular radius bisects chord | Congruence | Geometry | Khan Academy
Perpendicular radius bisects chord | Congruence | Geometry | Khan AcademySimple proof using RSH postulate to show that a radius perpendicular to a chord bisects itWatch the next lesson: https://www.khanacademy.org/math/geometry/congruent-triang…
- 7 Oct 11, 6:18pm -
30-60-90 triangle example problem | Right triangles and trigonometry | Geometry | Khan Academy
30-60-90 triangle example problem | Right triangles and trigonometry | Geometry | Khan AcademyUsing what we know about 30-60-90 triangles to solve what at first seems to be a challenging problemPractice this lesson yourself on KhanAcademy.org r…
- 5 Oct 11, 2:27pm -
The golden ratio | Introduction to Euclidean geometry | Geometry | Khan Academy
The golden ratio | Introduction to Euclidean geometry | Geometry | Khan AcademyAn introduction to one of the most amazing ideas/numbers in mathematicsWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-li…
- 5 Oct 11, 1:44pm -
45-45-90 triangle side ratios | Right triangles and trigonometry | Geometry | Khan Academy
45-45-90 triangle side ratios | Right triangles and trigonometry | Geometry | Khan AcademyShowing the ratios of the sides of a 45-45-90 triangle are 1:1:sqrt(2)Watch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_top…
- 4 Oct 11, 8:52pm -
30-60-90 triangle side ratios proof | Right triangles and trigonometry | Geometry | Khan Academy
30-60-90 triangle side ratios proof | Right triangles and trigonometry | Geometry | Khan AcademyProving the ratios between the sides of a 30-60-90 triangleWatch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic/sp…
- 4 Oct 11, 8:27pm -
Pythagorean theorem proof using similarity | Geometry | Khan Academy
Pythagorean theorem proof using similarity | Geometry | Khan AcademyProof of the Pythagorean Theorem using similarityPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/right_triangles_topic/py…
- 4 Oct 11, 5:49pm -
Finding area using similarity and congruence | Similarity | Geometry | Khan Academy
Finding area using similarity and congruence | Similarity | Geometry | Khan AcademyExample of using similarity and congruence to find the area of a trianglePractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org…
- 4 Oct 11, 5:47pm -
Similarity example where same side plays different roles | Similarity | Geometry | Khan Academy
Similarity example where same side plays different roles | Similarity | Geometry | Khan AcademyThe same side not corresponding to itself in two similar trianglesPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacadem…
- 3 Oct 11, 4:00pm -
Acute right and obtuse angles | Angles and intersecting lines | Geometry | Khan Academy
Acute right and obtuse angles | Angles and intersecting lines | Geometry | Khan AcademyWe briefly discussed the types of angles in the last tutorial but we'll delve a little deeper into acute, obtuse, and right angles here.Practice this lesson…
- 12 Apr 11, 5:39pm -
Cylinder volume and surface area | Perimeter, area, and volume | Geometry | Khan Academy
Cylinder volume and surface area | Perimeter, area, and volume | Geometry | Khan AcademyFinding the volume and surface area of a cylinderPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/basi…
- 12 Apr 11, 5:06pm -
Find the volume of a triangular prism and cube | Geometry | Khan Academy
Find the volume of a triangular prism and cube | Geometry | Khan AcademyIn this tutorial we'll practice finding solid geometry volume. Keep paper and pencil nearby in case you want to remember the formulas.Practice this lesson yourself on KhanA…
- 12 Apr 11, 4:40pm -
2003 AIME II problem 7 | AIME | Math for fun and glory | Khan Academy
2003 AIME II problem 7 | AIME | Math for fun and glory | Khan AcademyCreated by Sal Khan.Watch the next lesson: https://www.khanacademy.org/math/math-for-fun-and-glory/aime/2003-aime/v/2003-aime-ii-problem-8?utm_source=YT&utm_medium=Desc&utm_ca…
- 7 Jan 11, 7:29pm -
Rhombus diagonals | Quadrilaterals | Geometry | Khan Academy
Rhombus diagonals | Quadrilaterals | Geometry | Khan AcademyProof that the diagonals of a rhombus are perpendicular bisectors of each otherWatch the next lesson: https://www.khanacademy.org/math/geometry/analytic-geometry-topic/geometry-problem…
- 7 Jan 11, 7:26pm -
Triangle medians and centroids (2D proof) | Geometry | Khan Academy
Triangle medians and centroids (2D proof) | Geometry | Khan AcademyShowing that the centroid is 2/3 of the way along a medianWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/medians_centroids/v/medians-divide…
- 6 Jan 11, 11:40pm -
Triangle medians and centroids | Special properties and parts of triangles | Geometry | Khan Academy
Triangle medians and centroids | Special properties and parts of triangles | Geometry | Khan AcademySeeing that the centroid is 2/3 of the way along every medianWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-propertie…
- 6 Jan 11, 11:40pm -
The Pythagorean theorem intro | Right triangles and trigonometry | Geometry | Khan Academy
The Pythagorean theorem intro | Right triangles and trigonometry | Geometry | Khan AcademyIntroduction to the Pythagorean TheoremPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/right_triang…
- 9 Aug 10, 5:13pm -
Angles formed between transversals and parallel lines | Geometry | Khan Academy
Angles formed between transversals and parallel lines | Geometry | Khan AcademyAngles of parallel linesWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/old_angles/v/angles-of-parallel-lines-2?utm…
- 9 Aug 10, 4:54pm -
Angles of parallel lines 2 | Angles and intersecting lines | Geometry | Khan Academy
Angles of parallel lines 2 | Angles and intersecting lines | Geometry | Khan AcademyAngles of parallel lines examplesWatch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/old_angles/v/the-angle-game?u…
- 9 Aug 10, 4:52pm -
Area of diagonal generated triangles of rectangle are equal | Geometry | Khan Academy
Area of diagonal generated triangles of rectangle are equal | Geometry | Khan AcademyArea of Diagonal Generated Triangles of Rectangle are EqualWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/perimeter_area_tutor…
- 18 Jul 10, 3:26pm -
Proof: Right triangles inscribed in circles | High School Math | Khan Academy
Proof: Right triangles inscribed in circles | High School Math | Khan AcademyProof showing that a triangle inscribed in a circle having a diameter as one side is a right triangle. Created by Sal Khan.Watch the next lesson: https://www.khanacade…
- 19 Mar 10, 7:18pm -
Area of inscribed equilateral triangle (some basic trig used) | Circles | Geometry | Khan Academy
Area of inscribed equilateral triangle (some basic trig used) | Circles | Geometry | Khan AcademyProblem that requires us to figure out the area of an equilateral triangle inscribed in a circle (A little trigonometry used)Watch the next lesson:…
- 18 Mar 10, 7:04pm -
Inscribed angle theorem proof | High School Geometry | High School Math | Khan Academy
Inscribed angle theorem proof | High School Geometry | High School Math | Khan AcademyProving that an inscribed angle is half of a central angle that subtends the same arc. Created by Sal Khan.Watch the next lesson: https://www.khanacademy.org/…
- 18 Mar 10, 5:23pm -
Part 2 of proof of Heron's formula | Perimeter, area, and volume | Geometry | Khan Academy
Part 2 of proof of Heron's formula | Perimeter, area, and volume | Geometry | Khan AcademyShowing that the expression in part 1 is identical to Heron's FormulaWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/circu…
- 18 Mar 10, 12:46am -
Part 1 of proof of Heron's formula | Perimeter, area, and volume | Geometry | Khan Academy
Part 1 of proof of Heron's formula | Perimeter, area, and volume | Geometry | Khan AcademyPart 1 of the proof of Heron's FormulaWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-geometry/heron_formula_tutorial/v/part-2-of-t…
- 17 Mar 10, 10:30pm -
Heron's formula | Perimeter, area, and volume | Geometry | Khan Academy
Heron's formula | Perimeter, area, and volume | Geometry | Khan AcademyUsing Heron's Formula to determine the area of a triangle while only knowing the lengths of the sidesWatch the next lesson: https://www.khanacademy.org/math/geometry/basic-g…
- 17 Mar 10, 10:05pm -
Area of a circle
Area of a circleArea of a circle and how it relates to radius and diameterFrom:Khan AcademyViews:245509 989ratingsTime:06:45More inEducation
- 8 Nov 09, 7:06pm -
Circles: radius, diameter, circumference and Pi | Geometry | Khan Academy
Circles: radius, diameter, circumference and Pi | Geometry | Khan AcademyA circle is at the foundation of geometry and how its parts relate to each other is both completely logical and a wonder.Practice this lesson yourself on KhanAcademy.org r…
- 8 Nov 09, 7:06pm -
Area and Perimeter
Area and PerimeterArea of rectangles and triangles. Perimeter of rectangles.From:Khan AcademyViews:441440 909ratingsTime:12:20More inEducation
- 8 Nov 09, 7:06pm -
Similar triangles (part 2) | Similarity | Geometry | Khan Academy
Similar triangles (part 2) | Similarity | Geometry | Khan AcademyMore on similar trianglesWatch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic/pyth_theor/v/pythagorean-theorem?utm_source=YT&utm_medium=Desc&utm_…
- 11 Nov 07, 12:48am -
Similar triangles | Similarity | Geometry | Khan Academy
Similar triangles | Similarity | Geometry | Khan AcademyIntroduction to similar trianglesWatch the next lesson: https://www.khanacademy.org/math/geometry/similarity/old_school_similarity/v/similar-triangles-part-2?utm_source=YT&utm_medium=Desc&…
- 11 Nov 07, 12:48am -
Angle game (part 2) | Angles and intersecting lines | Geometry | Khan Academy
Angle game (part 2) | Angles and intersecting lines | Geometry | Khan AcademyMore examples of the Angle Game.Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/old_angles/v/acute-right-and-obtuse-a…
- 10 Nov 07, 11:42pm -
The angle game | Angles and intersecting lines | Geometry | Khan Academy
The angle game | Angles and intersecting lines | Geometry | Khan AcademyUsing what we know to solve for angles in the Angle Game.Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/old_angles/v/angl…
- 10 Nov 07, 10:30pm -
Angles (part 3) | Angles and intersecting lines | Geometry | Khan Academy
Angles (part 3) | Angles and intersecting lines | Geometry | Khan AcademyAngles formed when a transversal intersects parallel lines.Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular-lines/old_angles/v/a…
- 10 Nov 07, 6:48pm -
Angles (part 2) | Angles and intersecting lines | Geometry | Khan Academy
Angles (part 2) | Angles and intersecting lines | Geometry | Khan AcademyMore on complementary and supplementary angles. Introduction to opposite angles.Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-perpendicular…
- 10 Nov 07, 6:48pm -
Introduction to angles (old) | Angles and intersecting lines | Geometry | Khan Academy
Introduction to angles (old) | Angles and intersecting lines | Geometry | Khan AcademyWhat an angle is. Angles in a circle. Complementary and supplementary angles.Watch the next lesson: https://www.khanacademy.org/math/geometry/parallel-and-per…
- 10 Nov 07, 6:48pm -
45-45-90 triangles | Right triangles and trigonometry | Geometry | Khan Academy
45-45-90 triangles | Right triangles and trigonometry | Geometry | Khan AcademyIntroduction to 45-45-90 TrianglesWatch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic/special_right_triangles/v/intro-to-30-60-90-…
- 28 Oct 07, 4:49pm -
Pythagorean theorem II | Right triangles and trigonometry | Geometry | Khan Academy
Pythagorean theorem II | Right triangles and trigonometry | Geometry | Khan AcademyMore Pythagorean Theorem examples. Introduction to 45-45-90 triangles.Watch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic/pyth…
- 28 Oct 07, 4:49pm -
Intro to 30-60-90 triangles | Right triangles and trigonometry | Geometry | Khan Academy
Intro to 30-60-90 triangles | Right triangles and trigonometry | Geometry | Khan AcademyA few more 45-45-90 examples and an introduction to 30-60-90 triangles.Watch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topi…
- 28 Oct 07, 4:49pm -
30-60-90 Triangles II
30-60-90 Triangles IIMore examples using 30-60-90 triangles.More free lessons at: http://www.khanacademy.org/video?v=3mLUJSoh6i0From:Khan AcademyViews:108981 153ratingsTime:04:49More inEducation
- 28 Oct 07, 4:49pm -

Khan Academy - Geometry 97-114

Area of a regular hexagon | Right triangles and trigonometry | Geometry | Khan Academy
Area of a regular hexagon | Right triangles and trigonometry | Geometry | Khan AcademyUsing what we know about triangles to find the area of a regular hexagonWatch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic…
- 2 Nov 11, 9:03pm -
Problem involving angle derived from square and circle | Congruence | Geometry | Khan Academy
Problem involving angle derived from square and circle | Congruence | Geometry | Khan AcademyChallenging problem to find an anglePractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/congruent-tr…
- 2 Nov 11, 9:02pm -
Area of a parallelogram | Perimeter, area, and volume | Geometry | Khan Academy
Area of a parallelogram | Perimeter, area, and volume | Geometry | Khan AcademyGuess what's interesting about the opposite sides of a parallelogram? That's right....they are parallel! Let's find the area--base times heightPractice this lesson y…
- 1 Nov 11, 5:14pm -
Proof: Rhombus area half product of diagonal length | Quadrilaterals | Geometry | Khan Academy
Proof: Rhombus area half product of diagonal length | Quadrilaterals | Geometry | Khan AcademyShowing that we can find the area of a rhombus by taking half the product of the lengths of the diagonalsWatch the next lesson: https://www.khanacadem…
- 1 Nov 11, 4:09pm -
Proof: Rhombus diagonals are perpendicular bisectors | Quadrilaterals | Geometry | Khan Academy
Proof: Rhombus diagonals are perpendicular bisectors | Quadrilaterals | Geometry | Khan AcademyProving that the diagonals of a rhombus are perpendicularWatch the next lesson: https://www.khanacademy.org/math/geometry/quadrilaterals-and-polygons…
- 31 Oct 11, 7:58pm -
Proof: Opposite angles of parallelogram congruent | Quadrilaterals | Geometry | Khan Academy
Proof: Opposite angles of parallelogram congruent | Quadrilaterals | Geometry | Khan AcademyShowing that opposite angles of a parallelogram are congruentPractice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/ma…
- 31 Oct 11, 5:16pm -
Proof: Diagonals of a parallelogram bisect each other | Quadrilaterals | Geometry | Khan Academy
Proof: Diagonals of a parallelogram bisect each other | Quadrilaterals | Geometry | Khan AcademyProving that a quadrilateral is a parallelogram if and only if its diagonals bisect each otherWatch the next lesson: https://www.khanacademy.org/mat…
- 31 Oct 11, 5:15pm -
Proof: Opposite sides of parallelogram congruent | Quadrilaterals | Geometry | Khan Academy
Proof: Opposite sides of parallelogram congruent | Quadrilaterals | Geometry | Khan AcademyProving that a figure is a parallelogram if and only if opposite sides are congruentWatch the next lesson: https://www.khanacademy.org/math/geometry/quad…
- 31 Oct 11, 5:14pm -
Quadrilateral overview | Perimeter, area, and volume | Geometry | Khan Academy
Quadrilateral overview | Perimeter, area, and volume | Geometry | Khan Academy"Quad" means "four" and "lateral" means "line." A quadrilateral is literally a shape with four sides (lines) and four angles. Let's learn the difference between concave…
- 26 Oct 11, 6:59pm -
Common orthocenter and centroid | Geometry | Khan Academy
Common orthocenter and centroid | Geometry | Khan AcademyShowing that a triangle with the same point as the orthocenter and centroid is equilateralWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/triangle_pro…
- 25 Oct 11, 9:44pm -
Euler's line proof | Special properties and parts of triangles | Geometry | Khan Academy
Euler's line proof | Special properties and parts of triangles | Geometry | Khan AcademyProving the somewhat mystical result that the circumcenter, centroid and orthocenterWatch the next lesson: https://www.khanacademy.org/math/geometry/quadril…
- 24 Oct 11, 5:24pm -
Euler line | Special properties and parts of triangles | Geometry | Khan Academy
Euler line | Special properties and parts of triangles | Geometry | Khan AcademyThe magic and mystery of the Euler LineWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/triangle_property_review/v/euler-s-line-…
- 20 Oct 11, 2:11pm -
Review of triangle properties | Special properties and parts of triangles | Geometry | Khan Academy
Review of triangle properties | Special properties and parts of triangles | Geometry | Khan AcademyComparing perpendicular bisectors to angle bisectors to medians to altitudesWatch the next lesson: https://www.khanacademy.org/math/geometry/tria…
- 20 Oct 11, 1:46pm -
Proof: Triangle altitudes are concurrent (orthocenter) | Geometry | Khan Academy
Proof: Triangle altitudes are concurrent (orthocenter) | Geometry | Khan AcademyShowing that any triangle can be the medial triangle for some larger triangle. Using this to show that the altitudes of a triangle are concurrent (at the orthocenter)…
- 17 Oct 11, 11:02pm -
Median centroid right triangle example | Geometry | Khan Academy
Median centroid right triangle example | Geometry | Khan AcademyExample involving properties of mediansWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/altitudes/v/proof-triangle-altitudes-are-concurrent-orth…
- 17 Oct 11, 11:01pm -
Proving that the centroid is 2-3rds along the median | Geometry | Khan Academy
Proving that the centroid is 2-3rds along the median | Geometry | Khan AcademyShowing that the centroid divides each median into segments with a 2:1 ratio (or that the centroid is 2/3 along the median)Watch the next lesson: https://www.khanacad…
- 17 Oct 11, 4:41pm -
Exploring medial triangles | Special properties and parts of triangles | Geometry | Khan Academy
Exploring medial triangles | Special properties and parts of triangles | Geometry | Khan AcademyWhat a medial triangle is and its propertiesWatch the next lesson: https://www.khanacademy.org/math/geometry/triangle-properties/medians_centroids/v…
- 13 Oct 11, 11:28pm -