Online Geometry Problem 449: Congruent Tangent Circles, Diameter, Radius, Sagitta, Arc, Perpendicular, Chord, Triangle, Metric Relations

The figure shows a circle with diameter AC. GF=a is the sagitta of arc AB and DE=b is the sagitta of arc BC. Three congruent circles of radius x are tangent to each other and to the sides of the triangle ABC. Prove that .