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MathNet 2019-part-07 — 184 problems (EN–VI) Question 79

Math Olympiad Vault · MathNet 2019-part-07 — 184 problems (EN–VI)

Question 79

The inscribed circle of an acute triangle $ABC$ (with incenter $I$) touches sides $AB$ and $BC$ in points $C_1$ and $A_1$ respectively. Let $M$ be the midpoint of the side $AC$, and $N$ be the midpoint of an arc $ABC$ of the circumcircle of $ABC$. Also, let $P$ be the projection of a point $M$ to the segment $A_1C_1$. Prove the points $I$, $P$, and $N$ lie on the same line.
(Anton Trygub)

Question illustration
**Fig. 35**