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MathNet 2024-part-02 — 168 problems (EN–VI) Question 50

Math Olympiad Vault · MathNet 2024-part-02 — 168 problems (EN–VI)

Question 50

In an acute triangle $ABC$ with $AB \lt AC$, the altitudes $BE$ and $CF$ intersect at $H$. The tangent to the circumcircle of $ABC$ at $A$ intersects the circumcircle of $AEF$ at $T \neq A$. The circumcircles of $TBE$ and $TCF$ intersect at $K \neq T$. Prove that $\angle KHB = \angle ABC$.