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MathNet 2023-part-05 — 191 problems (EN–VI) Question 166

Math Olympiad Vault · MathNet 2023-part-05 — 191 problems (EN–VI)

Question 166

Let $ABC$ be a right-angled triangle with $\angle BAC = 90^\circ$, and let $E$ be the foot of the perpendicular from $A$ to $BC$. Let $Z \neq A$ be a point on the line $AB$ with $AB = BZ$. Let $(c_1)$ be the circumcircle of the triangle $BEZ$ and $(c_2)$ be an arbitrary circle passing through the points $A$ and $E$. Suppose $(c_1)$ meets the line $CZ$ again at the point $F$, and meets $(c_2)$ again at the point $N$. If $P$ is the other point of intersection of $(c_2)$ with $AF$, prove that the points $N, B, P$ are collinear.