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MathNet 2021 — Part 08 Question 83

Math Olympiad Vault · MathNet 2021 — Part 08

Question 83

Let $ABC$ be a triangle with $AB\ne AC$, let $I$ be its incenter, let $\gamma$ be its incircle, and let $D$ be the midpoint of $BC$. The tangent from $D$ to $\gamma$ other than $BC$ touches $\gamma$ at $E$. Prove that $AE$ and $DI$ are parallel.