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MathNet 2023-part-01 — 191 problems (EN–VI) Question 64

Math Olympiad Vault · MathNet 2023-part-01 — 191 problems (EN–VI)

Question 64

Let $ABC$ be a triangle with circumcenter $O$. Point $X$ is the intersection of the parallel line from $O$ to $AB$ with the perpendicular line to $AC$ from $C$. Let $Y$ be the point where the external bisector of $\angle BXC$ intersects with $AC$. Let $K$ be the projection of $X$ onto $BY$.
Prove that the lines $AK$, $XO$, $BC$ have a common point.