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MathNet 2023-part-04 — 191 problems (EN–VI) Question 5

Math Olympiad Vault · MathNet 2023-part-04 — 191 problems (EN–VI)

Question 5

Let $ABCD$ be a quadrilateral with $\angle DAB = \angle ABC$. The circumcircle of triangle $ABC$ intersects segment $AD$ at point $K$ and segment $CD$ at point $L$. Segment $AL$ intersects segment $CK$ at point $P$. If $\angle ADB = \angle PDC$, prove that $CP = CL$.