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MathNet 2005 — Part 02 Question 63

Math Olympiad Vault · MathNet 2005 — Part 02

Question 63

The extensions of the sides $AB$ and $CD$ of a convex quadrilateral $ABCD$ meet at point $P$ and the extensions of the sides $BC$ and $AD$ meet at point $Q$. The point $O$ from the interior of the quadrilateral is such that $\measuredangle BOP = \measuredangle DOQ$. Prove that $\measuredangle AOB + \measuredangle COD = 180^\circ$.