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.
AO = BO = CO => r
AP * BP = CO * PQ
(r - 20)(r + 20) = 8 * [sqrt(r2 + 202)]
Corrections:::
Second line: AP * BP = CP * PQ
