MathDB
Croatian mathematical olympiad, day 2 problem 3

Source:

April 10, 2011
geometrycircumcircleperpendicular bisectorprojective geometrypower of a pointradical axisgeometry unsolved

Problem Statement

Let KK and LL be the points on the semicircle with diameter ABAB. Denote intersection of AKAK and ALAL as TT and let NN be the point such that NN is on segment ABAB and line TNTN is perpendicular to ABAB. If UU is the intersection of perpendicular bisector of ABAB an KLKL and VV is a point on KLKL such that angles UAVUAV and UBVUBV are equal. Prove that NVNV is perpendicular to KLKL.