MathDB
10th EMC - Angle Trisection

Source: 10th European Mathematical Cup - Problem J2

December 22, 2021
emcEuropean Mathematical Cuptrisectorgeometrycircumcircle

Problem Statement

Let ABCABC be an acute-angled triangle such that AB<AC|AB|<|AC|. Let XX and YY be points on the minor arc BC{BC} of the circumcircle of ABCABC such that BX=XY=YC|BX|=|XY|=|YC|. Suppose that there exists a point NN on the segment AY\overline{AY} such that AB=AN=NC|AB|=|AN|=|NC|. Prove that the line NCNC passes through the midpoint of the segment AX\overline{AX}. \\ \\ (Ivan Novak)