Source: 2016 China Second Round Olympiad Problem 2
January 8, 2017
geometry
Problem Statement
Let X,Y be two points which lies on the line BC of △ABC(X,B,C,Ylies in sequence) such that BX⋅AC=CY⋅AB, O1,O2 are the circumcenters of △ACX,△ABY, O1O2∩AB=U,O1O2∩AC=V. Prove that △AUV is a isosceles triangle.