isosceles wanted, semicircle related Puerto Rico TST 2023.1.2
Source:
March 23, 2024
geometryisoscelessemicircle
Problem Statement
Consider a semicircle with center and diameter . Let be a point in the semicircle, different from and , and let be the midpoint of the arc . The line parallel to through intersects at the point . Prove that the triangle is isosceles.