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MathNet 2001 — Part 01 Question 156

Math Olympiad Vault · MathNet 2001 — Part 01

Question 156

Let $\triangle ABC$ be an acute-angled triangle with $O$ as its circumcenter. Let $P$ on line $BC$ be the foot of the altitude from $A$. Assume that $\angle BCA \ge \angle ABC + 30^\circ$. Prove that $\angle CAB + \angle COP \lt 90^\circ$.