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MathNet 2018-part-04 — 181 problems (EN–VI) Question 57

Math Olympiad Vault · MathNet 2018-part-04 — 181 problems (EN–VI)

Question 57

Let $ABC$ be an acute scalene triangle, and let $H$ and $O$ be its ortho-center and circumcenter, respectively. The line $OA$ crosses the altitudes from $B$ and $C$ of the triangle $ABC$ at $P$ and $Q$, respectively. Show that the center of the circle $HPQ$ lies on one of the medians of the triangle $ABC$.