MathDB
AK + KM = BL + LM wanted, AB = CK = CL given, perp. bisectors related

Source: Czech-Polish-Slovak Junior Match 2016, individual p4 CPSJ

January 20, 2020
geometryequal segmentsperpendicular bisector

Problem Statement

We are given an acute-angled triangle ABCABC with AB<AC<BCAB < AC < BC. Points KK and LL are chosen on segments ACAC and BCBC, respectively, so that AB=CK=CLAB = CK = CL. Perpendicular bisectors of segments AKAK and BLBL intersect the line ABAB at points PP and QQ, respectively. Segments KPKP and LQLQ intersect at point MM. Prove that AK+KM=BL+LMAK + KM = BL + LM.
Poland