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IMO 2024 — Complete Shortlist Question 20

IMO Shortlist · IMO 2024 — Complete Shortlist

Question 20

Let ABCD be a quadrilateral with AB parallel to CD and AB < CD. Lines AD and BC intersect at a point P. Point $ X \neq C $ on the circumcircle of triangle ABC is such that $ PC = PX $. Point $ Y \neq D $ on the circumcircle of triangle ABD is such that $ PD = PY $. Lines AX and BY intersect at Q.

Prove that PQ is parallel to AB.