Triangle exterior angle example (video) | Khan Academy
An exterior angle is formed outside a triangle by extending a side. Its measure is equal to the sum of the two non-adjacent interior angle measures, thanks to the fact that all angle measures in a …
Line and angle proofs (practice) | Khan Academy
Prove theorems about lines and angles using triangle congruence criteria and algebra.
Angles in a triangle sum to 180° proof (video) | Khan Academy
In that video, Sal took the fact that angles in a triangle sum to 180 degrees because this was true and he was trying to prove that corresponding angles are equal.
Similarity | High school geometry | Math | Khan Academy
Learn what it means for two figures to be similar, and how to determine whether two figures are similar or not. Use this concept to prove geometric theorems and solve some problems with …
Prove triangle properties (practice) | Khan Academy
Use transformations, line and angle relationships, and triangle congruence criteria to prove properties of triangles.
Angles of a triangle (review) | Geometry (article) | Khan Academy
Want to learn more about the interior angles in triangles proof? Check out this video.
Intro to angle bisector theorem (video) | Khan Academy
The Angle Bisector Theorem states that when an angle in a triangle is split into two equal angles, it divides the opposite side into two parts. The ratio of these parts will be the same as the ratio …
Relationships in triangles and quadrilaterals | Khan Academy
Theorems concerning triangle properties Learn Properties of congruence and equality Angles in a triangle sum to 180° proof
Triangle congruence review (article) | Khan Academy
Review the triangle congruence criteria and use them to determine congruent triangles.
Triangle inequality theorem (video) | Khan Academy
A triangle can't have an angle degree measure of 360 degrees. The biggest angle that a triangle can have is less than 180 degrees because the sum of the angle measures of a triangle is 180.