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MathNet 2016-part-07 — 182 problems (EN–VI) Question 166

Math Olympiad Vault · MathNet 2016-part-07 — 182 problems (EN–VI)

Question 166

Let $ABC$ be a triangle with incenter $I$ whose incircle is tangent to $\overline{BC}$, $\overline{CA}$, $\overline{AB}$ at $D, E, F$. Point $P$ lies on $\overline{EF}$ such that $\overline{DP} \perp \overline{EF}$. Ray $BP$ meets $\overline{AC}$ at $Y$ and ray $CP$ meets $\overline{AB}$ at $Z$. Point $Q$ is selected on the circumcircle of $\triangle AYZ$ so that $\overline{AQ} \perp \overline{BC}$.
Prove that $P, I, Q$ are collinear.

Question illustration