Khan Academy: Geometry: Other Triangle Congruence Postulates

Explains how to determine unknown side lengths of similar triangles by identifying corresponding sides and angles ans setting up proportions. The first example is a continuation from the video "Similar Triangles." Practice problems...

In this video tutorial [7:28], the instructor shows how to determine if two triangles are congruent using different triangle congruence postulates: SSS, SAS, ASA, AAS. Practice problems available.

Proof that if the legs of an isosceles triangle are congruent then the base angles are congruent and vice versa using triangle congruency postulates. The proof is written as a two-column proof. [9:03]

In this video tutorial [11:06], the instructor shows how to construct a two-column proof using triangle congruence postulates to prove that two line segments are perpendicular.

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...

This video tutorial [11:32] explains what a medial triangle is and proves that the medial triangle divides the original triangle into four congruent triangles. Proof uses triangle similarity and triangle congruence postulates.

Explains how to prove that a radius is perpendicular to a chord that it bisects by using the side-side-side triangle congruence postulate. [8:19]

Explains why SSA is not a valid postulate for proving triangle congruence. Practice problems available. This video [7:24] also appears in the Geometry: Triangles strand.

Demonstrates solutions to problems #4-6 of California Geometry released state test questions. Problems address understanding of proof by contradiction and proving triangles congruent. [11:56]

In this video tutorial [11:29], the instructor explains how to use triangle congruence to identify measures of corresponding sides and angles in triangles. Defines side-side-side (SSS) postulate. Practice problems available.