Let A, B, C be points on circle O such that AB is a diameter, and CO is perpendicular to AB. Let P be a point on OA, and let line CP intersect the circle again at Q. If OP = 20 and PQ = 8, find r^2, where r is the radius of the circle.
r^2 = 20.
QP * PC = AP * PB
8 * sqrt(r2 + 202) = (r - 20)*(r + 20)
r = 25.70069473 r2 = 660.5257097
