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%I #5 Oct 01 2024 07:38:34
%S 9,9,5,4,7,3,7,5,5,6,5,2,7,5,3,3,6,7,0,9,3,0,1,2,2,8,9,9,4,4,4,5,3,7,
%T 3,8,4,9,4,2,2,1,6,2,7,1,8,7,4,0,6,8,0,9,9,5,9,8,5,9,5,4,2,4,9,1,7,5,
%U 3,6,0,6,4,3,9,7,8,8,2,7,1,3,2,7,1,9,4,3,8,5,3,1,5,3,9,6,4,9,1,6,4,5,7,5,8
%N Decimal expansion of the area of Moss's egg constructed from a unit-hypotenuse right isosceles triangle.
%C Moss's egg is an oval named by Dixon (1987) after Stephanie Moss. It is formed by four circular arcs. The shape is composed of the area of a half disk of radius 1/2, circular sector with radius 1-sqrt(2)/2 and central angle Pi/2, and two partially overlapping circular sectors with radius 1 and central angle Pi/4, whose common area is of the unit-hypotenuse right isosceles triangle.
%C The perimeter of the shape is (3-sqrt(2)/2)*Pi/2.
%D Robert Dixon, Mathographics, New York: Dover, 1987. See p. 5.
%D Anna Weltman, Not Your Average Maths Book, Wide Eyed Editions, 2022. See p. 43.
%H Michael Borcherds and Bill Lombard, <a href="https://www.geogebra.org/m/eKMNypAj">Moss Egg by Robert Dixon</a>, GeoGebra.
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MosssEgg.html">Moss's Egg</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Moss%27s_egg">Moss's egg</a>.
%F Equals ((3-sqrt(2))*Pi - 1)/4.
%e 0.99547375565275336709301228994445373849422162718740...
%t RealDigits[((3 - Sqrt[2])*Pi - 1)/4, 10, 120][[1]]
%o (PARI) ((3-quadgen(8))*Pi - 1)/4
%Y Similar constants: A093731, A259830, A336266, A336308.
%K nonn,cons
%O 0,1
%A _Amiram Eldar_, Sep 30 2024