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International Mathematical Olympiad 2016 — Official contest Question 1

IMO · International Mathematical Olympiad 2016 — Official contest

Question 1

Triangle $BCF$ has a right angle at $B$. Let $A$ be the point on line $CF$ such that $FA=FB$ and $F$ lies between $A$ and $C$. Point $D$ is chosen so that $DA=DC$ and $AC$ is the bisector of $\angle DAB$. Point $E$ is chosen so that $EA=ED$ and $AD$ is the bisector of $\angle EAC$. Let $M$ be the midpoint of $CF$. Let $X$ be the point such that $AMXE$ is a parallelogram, where $AM\parallel EX$ and $AE\parallel MX$. Prove that lines $BD,FX,ME$ are concurrent.