Shortlist 2017/G3
Source: Shortlist 2017, Moldova TST 2018
July 10, 2018
geometryIMO ShortlistAngle Chasingprojective geometrysimilar trianglesISL 2017G3
Problem Statement
Let be the circumcenter of an acute triangle . Line intersects the altitudes of through and at and , respectively. The altitudes meet at . Prove that the circumcenter of triangle lies on a median of triangle .