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MathNet 2023-part-03 — 191 problems (EN–VI) Question 38

Math Olympiad Vault · MathNet 2023-part-03 — 191 problems (EN–VI)

Question 38

Given a cyclic quadrilateral $ABCD$ with circumcenter $O$. Let $E$ be the intersection of $AD$ and $BC$, and $F$ be the intersection of $AC$ and $BD$. Circle $\omega$ is tangent to $BD$ and $AC$. $QP$ is a diameter of $\omega$ such that $F$ is the orthocenter of triangle $QEP$. Prove that $EO$ passes through the center of $\omega$.