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Medians of right triangles form bisecting lines

Source: 2019 Baltic Way P14

November 18, 2019
geometry

Problem Statement

Let ABCABC be a triangle with ABC=90\angle ABC = 90^{\circ}, and let HH be the foot of the altitude from BB. The points MM and NN are the midpoints of the segments AHAH and CHCH, respectively. Let PP and QQ be the second points of intersection of the circumcircle of the triangle ABCABC with the lines BMBM and BNBN, respectively. The segments AQAQ and CPCP intersect at the point RR. Prove that the line BRBR passes through the midpoint of the segment MNMN.