Cyclic quadrilateral ABCD with CD^2=AD.ED; E=DA∩CB
Source: Czech-Polish-Slovak Match 2007-P3
September 14, 2011
geometrycircumcirclegeometry proposed
Problem Statement
A convex quadrilateral inscribed in a circle has the property that the rays and meet at a point for which CD^2=AD\cdot ED. The perpendicular to at intersects again at point Prove that the segments and are congruent if and only if the circumcenter
of lies on