find the size of an angle, a nice problem proposed by Greece
Source: bmo 1991
April 23, 2007
geometrygeometric transformationreflectionparallelogramtrapezoidgeometry proposed
Problem Statement
Let be an acute triangle inscribed in a circle centered at . Let be a point on the small arc of the triangle's circumcircle. The perpendicular dropped from on the ray intersects the sides and at the points and , respectively. Similarly, the perpendicular dropped from on the ray intersects the sides and at and , respectively. Assume that . Find the size of the angle in terms of the angles of the triangle .