MathDB
XY _|_ AM if RX, SY _|_ DE, MD = ME, AB, AC tangents of (O)

Source: 2021 Saudi Arabia Training Lists p6 https://artofproblemsolving.com/community/c2758131_2021_saudi_arabia_training_tests

January 4, 2022
geometryperpendicularTangents

Problem Statement

Let AA be a point lies outside circle (O)(O) and tangent lines ABAB, ACAC of (O)(O). Consider points D,E,MD, E, M on (O)(O) such that MD=MEMD = ME. The line DEDE cuts MBMB, MCMC at R,SR, S. Take XOBX \in OB, YOCY \in OC such that RX,SYDERX, SY \perp DE. Prove that XYAMXY \perp AM.