MathDB
Turkey NMO 2011 Problem 2

Source:

December 10, 2011
geometrycircumcircletrigonometrygeometric transformationreflectionperpendicular bisectorcyclic quadrilateral

Problem Statement

Let ABCABC be a triangle D[BC]D\in[BC] (different than AA and BB).EE is the midpoint of [CD][CD]. F[AC]F\in[AC] such that FEC^=90\widehat{FEC}=90 and AF.BC=AC.EC.|AF|.|BC|=|AC|.|EC|. Circumcircle of ADCADC intersect [AB][AB] at GG different than AA.Prove that tangent to circumcircle of AGFAGF at FF is touch circumcircle of BGEBGE too.