Geometry Problem 812: Four Tangent Circles, Common Tangent Line, Diameter, Collinear Centers, and Area. Perfect for High School and Mathematics Education!

The figure below illustrates four tangent circles with diameters AB, BC, CD, and AD. The line EFG is the common tangent to circles AB, BC, and CD at points E, F, and G, respectively. Given that EF = a and FG = b, the objective is to prove the formula for the shaded area: .

Four Circles, Tangent, Common Tangent Line, Area

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