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MathNet 2017-part-06 — 176 problems (EN–VI) Question 140

Math Olympiad Vault · MathNet 2017-part-06 — 176 problems (EN–VI)

Question 140

In triangle $ABC$, $AB = AC \ne BC$, and $I$ is its incenter. Line $BI$ meets $AC$ at $D$. The line through $D$ perpendicular to $AC$ meets $AI$ at $E$. Prove that the reflection of $I$ in line $AC$ lies on the circumcircle of triangle $BDE$.