Skip to content / Đến nội dung
ThichHocToan.com

MathNet 2010 — Part 03 Question 61

Math Olympiad Vault · MathNet 2010 — Part 03

Question 61

Let $ABC$ be an acute-angled triangle with altitude $AK$. Let $H$ be its orthocentre and $O$ be its circumcentre. Suppose $KOH$ is an acute-angled triangle and $P$ its circumcentre. Let $Q$ be the reflection of $P$ in the line $HO$. Show that $Q$ lies on the line joining the mid-points of $AB$ and $AC$.