Khan Academy
Khan Academy: Geometry: Incenter and Incircles of a Triangle
Explains that the intersection of the three angle bisectors of a triangle form the incenter of the triangle. [7:58]
Khan Academy
Khan Academy: Proving That the Centroid Is 2 3rds Along the Median
This video tutorial [6:56] shows a proof that the centroid is located two-thrids of the way along each median. Proof is done algebraically.
Khan Academy
Khan Academy: Geometry: Common Orthocenter and Centroid
Proves that if the orthocenter and centroid are the same point in a triangle then the triangle is a right triangle. [6:25]
Khan Academy
Khan Academy: Geometry: Euler Line
Demonstrates that the circumcenter, orthocenter, and centroid of a triangle all lie on a line called an Euler line. [6:12]
Khan Academy
Khan Academy: Geometry: Three Points Defining a Circle
Demonstates that any three non-collinear points can be used to define a unique triangle with a unique circumcenter and circumradius. These, in turn, define a unique circle. The center of the circle is the circumcenter of the triangle....
Khan Academy
Khan Academy: Geometry: Median Centroid Right Triangle Example
This video tutorial [9:00]explains how to find various measures of triangles formed by the medians of a right triangle. Based on the properties of the medians of a triangle, properties of centroids, and the Pythagorean theorem.
Khan Academy
Khan Academy: Review of Triangle Properties
Provides a review of perpendicular bisectors, angle bisectors, medians, and altitudes and the special points of concurrency formed by these parts of a triangle. The points of concurrency are the circumcenter, incenter, centroid,and...
Khan Academy
Khan Academy: Geometry: Circumcenter of a Right Triangle
Proves that the circumcenter of a right triangle is the midpoint of the hypotenuse. [5:42]
Khan Academy
Khan Academy: Geometry: Circumcenter of a Triangle
Explains using multiple proofs that a point on a perpendicular bisector is equidistant from the endpoints of the segment it bisects. Proofs use triangle congruency postulates. Lays the foundation for understanding the circumcenter of a...
Khan Academy
Khan Academy: Triangles: Proving That the Centroid Is 2 3 Rds Along the Median
This video demonstrates that the centroid divides each median into segments with a 2:1 ratio (or that the centroid is 2/3 along the median).
Khan Academy
Khan Academy: Triangles: Euler Line
A video demonstration of the magic and mystery of the Euler Line.
Khan Academy
Khan Academy: Triangles: Proof: Triangle Altitudes Are Concurrent (Orthocenter)
Demostrates how to take any triangle and make it become the medial triangle of a larger triangle. Also explains that the three altitudes of a triangle are concurrent. [10:01]
Khan Academy
Khan Academy: Triangles: Median Centroid Right Triangle Example
This video demonstrates how to find various measures of triangles formed by the medians of a right triangle.
Khan Academy
Khan Academy: Triangles: Review of Triangle Properties
Provides a review of perpendicular bisectors, angle bisectors, medians, and altitudes and the special points of concurrency formed by these parts of a triangle.
Khan Academy
Khan Academy: Geometry: Euler's Line Proof
Proves that the circumcenter, orthocenter, and centroid all lie on the same line, the Euler line. Proof relies on understanding of properties of similar triangles and properties of special parts of a triangle. [9:50]