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IMO 2007 — Complete Shortlist Question 18

IMO Shortlist · IMO 2007 — Complete Shortlist

Question 18

The diagonals of a trapezoid $A B C D$ intersect at point $P$. Point $Q$ lies between the parallel lines $B C$ and $A D$ such that $\angle A Q D=\angle C Q B$, and line $C D$ separates points $P$ and $Q$. Prove that $\angle B Q P=\angle D A Q$.