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KöMaL problem A, 2019

Geometry Difficulty 9.0 IMO level Prove it Hungary

Let PP be a point inside the acute triangle ABCABC, and let QQ be the isogonal conjugate of PP. Let LL, MM and NN be the midpoints of the shorter arcs BCBC, CACA and ABAB of the circumcircle of ABCABC, respectively. Let XAX_A be the intersection of ray LQLQ and circle PBCPBC, let XBX_B be the intersection of ray MQMQ and circle PCAPCA, and let XCX_C be the intersection of ray NQNQ and circle PABPAB. Prove that PP, XAX_A, XBX_B and XCX_C are concyclic or coincide.

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