MathDB
MR bisects <AMD, convex ABCD with equal diagonals

Source: III Soros Olympiad 1996-97 R1 10.5 https://artofproblemsolving.com/community/c2416727_soros_olympiad_in_mathematics

May 29, 2024
geometry

Problem Statement

The diagonals of a convex quadrilateral ABCDABCD are equal to each other and intersect at point MM. Points KK and LL are taken on ABAB and CDCD, respectively, so that AKKB=DLLC\frac{AK}{KB}=\frac{DL}{LC}. Lines ABAB and KDKD intersect at point PP. Prove that MPMP is the bisector of angle AMDAMD.