Tag: triangles

What is a perpendicular bisector? A perpendicular bisector of a line segment is a line that makes a 90-degree angle (a right angle) at the midpoint of a segment. In the figure, line b is the perpendicular bisector of line segment AB at C. This implies AC=CB and the measure of the angles at C

Theorem. The sum of the interior angles of any triangle is 180°. Here are three proofs for the sum of angles of triangles. Proof 1 uses the fact that the alternate interior angles formed by a transversal with two parallel lines are congruent. Proof 2 uses the exterior angle theorem. Proof 3 uses the idea