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SMO 2010 Open Round 2 Question 1

SMO · SMO 2010 Open Round 2

Question 1

Let $CD$ be a chord of a circle $\Gamma_1$ and $AB$ a diameter of $\Gamma_1$, perpendicular to $CD$ at $N$, with $AN\gt NB$. A circle $\Gamma_2$ centred at $C$ with radius $CN$ intersects $\Gamma_1$ at $P,Q$. The line $PQ$ intersects $CD$ at $M$ and $AC$ at $K$; the extension of $NK$ meets $\Gamma_2$ at $L$. Prove that $PQ$ is perpendicular to $AL$.