IMO Shortlist 2016 problem G4
Dodao/la:
arhiva3. listopada 2019. Let $ABC$ be a triangle with $AB = AC \neq BC$ and let $I$ be its incentre. The line $BI$ meets $AC$ at $D$, and the line through $D$ perpendicular to $AC$ meets $AI$ at $E$. Prove that the reflection of $I$ in $AC$ lies on the circumcircle of triangle $BDE$.
Izvor: https://www.imo-official.org/problems/IMO2016SL.pdf