D,E D, E\,D,E and F F\,F are points on the circumference of a circle, centre OOO. GFH GFH\,GFH is a tangent to the circle at point FFF.
A geometric diagram shows a circle with center OOO. A horizontal line GFH GFH\,GFH is tangent to the circle at point FFF. Points D D\,D and E E\,E are on the circumference. Chords DF DF\,DF and EF EF\,EF are drawn.
Prove that angle HFE HFE\,HFE and angle FDE FDE\,FDE are equal.