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. Prove that $BD,FX$ and $ME$ are concurrent.
IMO 2016 problem1 ผมhintให้ครับ1.ไล่มุม 2.วาดวงกลมล้อมรอบBCF 3.อะไรcollinearกันบ้าง 4.หาสี่เหลี่ยมด้านขนานเยอะๆ
