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Tuymaada P2 senior

Source: tuymaada 2022 senior P2

July 3, 2022
geometry

Problem Statement

Two circles w1w_{1} and w2w_{2} of different radii touch externally at LL. A line touches w1w_{1} at AA and w2w_{2} at BB (the points AA and BB are different from LL). A point XX is chosen in the plane. YY and ZZ are the second points of intersection of the lines XAXA and XBXB with w1w_{1} and w2w_{2} respectively. Prove that all XX such that ABYZAB||Y Z belong to one circle.