Gardner's Problem

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A red metal sheet has the shape of a two-foot square with semicircles on opposite sides. If a disk with a diameter of two feet is removed from the center, what is the area of the remaining metal?
Contributed by: Izidor Hafner (May 2014)
Open content licensed under CC BY-NC-SA
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Reference
[1] M. Gardner, The Colossal Book of Short Puzzles and Problems, (D. Richards, ed.), New York: W. W. Norton & Company, 2006 p. 109.
Permanent Citation
"Gardner's Problem"
http://demonstrations.wolfram.com/GardnersProblem/
Wolfram Demonstrations Project
Published: May 23 2014