In an isosceles triangle $ABC$ with an angle $\angle A= 20^o$ and base $BC=12$ point $E$ on the side $AC$ is chosen such that $\angle ABE= 30^o$ , and point $F$ on the side $AB$ such that $EF = FC$ . Find the length of $FC$.
Problem
Source: December 2020 Ukraine Geometry Olympiad VIII p4
Tags: geometry, isosceles, angles, equal segments