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MathNet 2019-part-06 — 184 problems (EN–VI) Question 113

Math Olympiad Vault · MathNet 2019-part-06 — 184 problems (EN–VI)

Question 113

A triangle $A B C$ is given. Let $D$ and $E$ be points lying on the rays $C A$ and $C B$, respectively, but not on the sides of triangle $A B C$, such that $|A D|=|B E|=|A B|$. Let $F$ be the intersection of the line through the point $E$ parallel to $A C$ and the line through the point $D$ parallel to $B C$. Denote the intersection of the lines $A E$ and $B D$ by $G$. Prove that the line $F G$ is the bisector of the angle $\angle E F D$.