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MathNet 2012 Question 95

Math Olympiad Vault · MathNet 2012

Question 95

Let $ABC$ be an acute triangle with circumcenter $O$. Let $P,Q$ be the intersections other than $A$ of the altitude from $A$ and the extended line $AO$, respectively, with the circumcircle of $ABC$.

a. Prove that angles $BAP$ and $QAC$ are equal.

b. Prove that triangles $BCP$ and $CBQ$ are congruent.

c. If $M,N$ are the midpoints of $AB,AC$, prove that the area of quadrilateral $ABPC$ is four times that of quadrilateral $AMON$.