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MathNet 2015-part-02 — 191 problems (EN–VI) Question 89

Math Olympiad Vault · MathNet 2015-part-02 — 191 problems (EN–VI)

Question 89

Let $I$ be the incentre of the triangle $ABC$ and let $D$ be the point on side $AC$ such that $|AB| = |DB|$. Incircle of the triangle $BCD$ touches the lines $AC$ and $BD$ in points $E$ and $F$, respectively. Prove that the line $EF$ passes through the midpoint of the segment $DI$.