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geometry junior
Problem
Four circles of radius are arranged as shown. Their centers are the vertices of a square. The area of the shaded region is closest to 
(A)
(B)
(C)
(D)
Solution
The side of the square of made up of two radii, and the area of the square is . The unshaded region of the square is composed of four quarter circles, and has the area of one circle, which is . The area of the shaded region is which less than , closest to .
Final answer
A