2022 OIM Problems/Problem 1

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Problem

Let $ABC$ be an equilateral triangle with circumcenter $O$ and circumcircle $\Gamma$. Let $D$ be a point on the minor arc $BC$, with $DB > DC$. The perpendicular bisector of $OD$ intersects $\Gamma$ at $E$ and $F$, with $E$ on the minor arc $BC$. Let $P$ be the intersection point of lines $BE$ and $CF$. Prove that $PD$ is perpendicular to $BC$.

Solution

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See also

https://sites.google.com/uan.edu.co/oim-2022/inicio