Online Geometry Problems, High School, College

Online Geometry Problem 485: Square, Side, Circles, Tangent, Radius, Measurement

The figure shows a square ABCD of side a. Circles C1, C2, C3, C4, are tangent to each other and to the sides of the square. Circles C1 and C2, are congruent. Circles C3 and C4,are congruent with radii x. Prove that Formula to prove.
 

Square, Circles, Radius, Side