MathDB
Benelux Mathematical Olympiad 2016, Problem 4

Source:

May 1, 2016
geometry

Problem Statement

A circle ω\omega passes through the two vertices BB and CC of a triangle ABC.ABC. Furthermore, ω\omega intersects segment ACAC in DCD\ne C and segment ABAB in EB.E\ne B. On the ray from BB through DD lies a point KK such that BK=AC,|BK| = |AC|, and on the ray from CC through EE lies a point LL such that CL=AB.|CL| = |AB|. Show that the circumcentre OO of triangle AKLAKL lies on ω\omega.