I'm trying to find an equilateral triangle with its height given. I've done the following: Triangle
Let $C,D$ be points in the intersection of two circunferences of same radius and center $A$ and $B$. Then, I constructed the bisector of $CA$ and $DA$ and they cut in $E$ and $F$ on the circunference of center $A$
I have to prove that the triangle $BEF$ is equilateral but I don't know how to prove it.