MathDB
Circumcircles and intersections madness

Source: Germany VAIMO 2015 - #3

July 11, 2015
geometrycircumcircleIntersection

Problem Statement

Let ABCABC be an acute triangle with ABAC|AB| \neq |AC| and the midpoints of segments [AB][AB] and [AC][AC] be DD resp. EE. The circumcircles of the triangles BCDBCD and BCEBCE intersect the circumcircle of triangle ADEADE in PP resp. QQ with PDP \neq D and QEQ \neq E. Prove AP=AQ|AP|=|AQ|.
(Notation: |\cdot| denotes the length of a segment and [][\cdot] denotes the line segment.)