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perpendicular bisectors of PQ bisects two segments AO, BC, altitudes

Source: 2021 Saudi Arabia Training Lists p3 https://artofproblemsolving.com/community/c2758131_2021_saudi_arabia_training_tests

January 4, 2022
geometrybisects segmentperpendicular bisector

Problem Statement

Let ABCABC be an acute, non-isosceles triangle inscribed in (O) and BBBB', CCCC' are altitudes. Denote E,FE, F as the intersections of BBBB', CCCC' with (O)(O) and D,P,QD, P, Q are projections of AA on BCBC, CECE, BFBF. Prove that the perpendicular bisectors of PQPQ bisects two segments AOAO, BCBC.