circle problem
Source: Central American Olympiad 2001, problem 2
August 12, 2009
Problem Statement
Let be the diameter of a circle with a center and radius . Let and be two points on the circle such that and intersect at a point situated inside of the circle, and \angle AQB\equal{} 2 \angle COD. Let be a point that intersects the tangents to the circle that pass through the points and .
Determine the length of segment .