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MathNet 2022-part-03 — 197 problems (EN–VI) Question 159

Math Olympiad Vault · MathNet 2022-part-03 — 197 problems (EN–VI)

Question 159

Let $ABC$ be an acute triangle, and let $D$ be the foot of the altitude from $A$. The circle with centre $A$ passing through $D$ intersects the circumcircle of triangle $ABC$ in $X$ and $Y$, in such a way that the order of the points on this circumcircle is: $A$, $X$, $B$, $C$, $Y$. Show that $\angle BXD = \angle CYD$.