Given a triangle ABC, let m and n be the perpendicular bisectors of sides AB and BC, respectively. Let O be the intersection of m and n. Recall that in Theorem 1.1.3 we proved that O is the center of the circumscribed circle, that is, a circle containing the vertices A, B, and C of the triangle. Use the Two-Reflections Theorem to prove that the inscribed angle ABC is measured by half the intercepted arc.