MathDB
Serbia Junior Balkan TST 2015

Source:

May 25, 2015
geometry

Problem Statement

The diagonals ADAD, BEBE, CFCF of cyclic hexagon ABCDEFABCDEF intersect in SS and ABAB is parallel to CFCF and lines DEDE and CFCF intersect each other in MM. Let NN be a point such that MM is the midpoint of SNSN. Prove that circumcircle of ADN\triangle ADN is passing through midpoint of segment CFCF.