Geometric Artwork of Problem 76. Square, Circle and
Area. PicSketch for iPad

Given a square ABCD 1, the inscribed
circle 2, the arc BD of center A. S is the area of the lune EF,
S_{1}, S_{2}, and S_{3} are the shaded
areas. Prove that S = S_{1}
+ S_{2} + S_{3}.
See also: Problem
76.