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MathNet 2021 — Part 11 Question 5

Math Olympiad Vault · MathNet 2021 — Part 11

Question 5

Let $ABC$ be an acute, non-isosceles triangle with circumcenter $O$ and incenter $I$. The incircle $(I)$ touches $BC$, $CA$, and $AB$ at $D$, $E$, and $F$, respectively. Suppose that $EF$ meets $(O)$ at $P$ and $Q$. Prove that the circle $(PQD)$ passes through the midpoint of $BC$.