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MathNet 2001 — Part 01 Question 63

Math Olympiad Vault · MathNet 2001 — Part 01

Question 63

$ABC$ is a triangle. The incircle has center $I$ and touches the sides $BC$, $CA$, $AB$ at $D$, $E$, $F$ respectively. The rays $BI$ and $CI$ meet the line $EF$ at $P$ and $Q$ respectively. Show that if $DPQ$ is isosceles, then $ABC$ is isosceles.