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MathNet 2017-part-04 — 176 problems (EN–VI) Question 166

Math Olympiad Vault · MathNet 2017-part-04 — 176 problems (EN–VI)

Question 166

Let $I$ be the incenter of the scalene triangle $ABC$, with $AB \lt AC$, and let $I'$ be the reflection of point $I$ in the line $BC$. The angle bisector $AI$ meets the side $BC$ at $D$ and the circumcircle of $ABC$ at $E$. The line $EI'$ meets the circumcircle at $F$. Prove that $\frac{AI}{IE} = \frac{ID}{DE}$ and $IA = IF$.