what is triangle sum theorem and the exterior angles theorem
Angle Sum Theorem. The Angle Sum Theorem gives an important result about triangles, which is used in many algebra and geometry problems. We give the proof below. Theorem: The sum of the measures of the interior angles of a triangle is 180 Â°. Given: Î X Y Z. Prove: m â  1 + m â  2 + m â  3 = 180 Â°
In the picture below, the angles â ABC, â BCA and â CAB are the three interior angles of the triangle. An exterior angle is formed by extending one of the sides of the triangle; the angle between the extended side and the other side is the exterior angle. In the picture, angle â ACD is an exterior angle. Euclid's exterior angle theorem