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MathNet 2016-part-02 — 184 problems (EN–VI) Question 1

Math Olympiad Vault · MathNet 2016-part-02 — 184 problems (EN–VI)

Question 1

Let $ABC$ be an acute-angled triangle with $AB \lt AC$. Tangent to its circumcircle $\Omega$ at $A$ intersects the line $BC$ at $D$. Let $G$ be the centroid of $ABC$ and let $AG$ meet $\Omega$ again at $H \neq A$. Suppose the line $DG$ intersects the lines $AB$ and $AC$ at $E$ and $F$, respectively. Prove that $\angle EHG = \angle GHF$.