Bride's Chair
One name for the figure used by Euclid to prove the Pythagorean theorem. It is sometimes also known as the "windmill."
See also
Peacock TailExplore with Wolfram|Alpha
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References
Bogomolny, A. "Bride's Chair." https://www.cut-the-knot.org/ctk/BridesChair.shtml.Wells, D. The Penguin Dictionary of Curious and Interesting Geometry. London, England: Penguin, p. 203, 1991.Referenced on Wolfram|Alpha
Bride's ChairCite this as:
Weisstein, Eric W. "Bride's Chair." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BridesChair.html