MathDB
Geometry

Source: 2016 China Second Round Olympiad Problem 2

January 8, 2017
geometry

Problem Statement

Let X,YX,Y be two points which lies on the line BCBC of ABC(X,B,C,Ylies in sequence)\triangle ABC(X,B,C,Y\text{lies in sequence}) such that BXAC=CYABBX\cdot AC=CY\cdot AB, O1,O2O_1,O_2 are the circumcenters of ACX,ABY\triangle ACX,\triangle ABY, O1O2AB=U,O1O2AC=VO_1O_2\cap AB=U,O_1O_2\cap AC=V. Prove that AUV\triangle AUV is a isosceles triangle.