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MathNet 2023-part-03 — 191 problems (EN–VI) Question 56

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

Question 56

Points $B$ and $C$ are fixed on the circle $\omega$. Denote by $M$ the midpoint of $BC$. Let $A$ be a variable point on $\omega$, and $H$ be the orthocenter of triangle $ABC$. The perpendicular from $H$ to $MH$ intersects lines $AB$ and $AC$ at points $X$ and $Y$, respectively. Prove that as point $A$ moves on $\omega$, the orthocenter of triangle $AXY$ also moves on a circle.