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MathNet 2023-part-01 — 191 problems (EN–VI) Question 106

Math Olympiad Vault · MathNet 2023-part-01 — 191 problems (EN–VI)

Question 106

Let $\omega_1$ and $\omega_2$ be circles with no common points. Points $M$ and $N$ are chosen on the circles $\omega_1$ and $\omega_2$, respectively, such that the tangent to the circle $\omega_1$ at $M$ and the tangent to the circle $\omega_2$ at $N$ intersect at $P$ and $\triangle PMN$ is an isosceles triangle with apex $P$. The circles $\omega_1$ and $\omega_2$ meet the segment $MN$ again at $A$ and $B$, respectively. The line $PA$ meets the circle $\omega_1$ again at $C$ and the line $PB$ meets the circle $\omega_2$ again at $D$. Prove that $\angle BCN = \angle ADM$.