r1980

Let r be a line through the circumcenter O. Let ra, rb, rc be the reflections on r of the perpendicular bisectors. Let A', B', C' be the orthogonal projections of A, B, C on ra, rb, rc. The triangles ABC, A'B'C' are homothetic and orthologic; the homothetic center and the two orthologic centers are collinear.


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