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2017 IGO Advanced P3

Source: 4th Iranian Geometry Olympiad (Advanced) P3

September 15, 2017

Problem Statement

Let OO be the circumcenter of triangle ABCABC. Line COCO intersects the altitude from AA at point KK. Let P,MP,M be the midpoints of AKAK, ACAC respectively. If POPO intersects BCBC at YY, and the circumcircle of triangle BCMBCM meets ABAB at XX, prove that BXOYBXOY is cyclic.
Proposed by Ali Daeinabi - Hamid Pardazi