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MathNet 2022-part-05 — 197 problems (EN–VI) Question 122

Math Olympiad Vault · MathNet 2022-part-05 — 197 problems (EN–VI)

Question 122

Let $ABC$ be an acute triangle with circumcircle $\omega$ centered at $O$. A point $P$ is chosen on the extension of the segment $BC$. The line $AP$ meets $\omega$ again at $L$. Let $K$ be the reflection of $L$ over the line $OP$ and $M$ be the point of intersection of lines $AK$ and $OP$. Prove that $\angle OMB + \angle OMC = 180^\circ$.