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MathNet 2022-part-01 — 197 problems (EN–VI) Question 124

Math Olympiad Vault · MathNet 2022-part-01 — 197 problems (EN–VI)

Question 124

Let $\triangle ABC$ be a triangle with an incenter $I$. The line $CI$ intersects for a second time the circumcircle of $\triangle ABC$ at $L$, where $CI = 2 \cdot IL$. Points $M$ and $N$ lie on the segment $AB$, such that $\angle AIM = \angle BIN = 90^\circ$. Prove that $AB = 2 \cdot MN$.