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A231984
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Decimal expansion of the solid angle (in deg^2) of a spherical square having sides of one degree.
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6
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9, 9, 9, 9, 7, 4, 6, 1, 6, 4, 3, 9, 2, 7, 8, 6, 5, 4, 3, 2, 1, 9, 8, 5, 0, 9, 4, 7, 8, 4, 9, 6, 8, 2, 2, 5, 5, 1, 7, 9, 5, 9, 1, 5, 2, 4, 1, 8, 5, 7, 6, 4, 5, 2, 7, 4, 0, 6, 4, 6, 7, 2, 8, 4, 2, 8, 1, 4, 8, 7, 7, 7, 6, 0, 7, 1, 7, 3, 3, 6, 5, 8, 1, 8, 1, 5, 1, 7, 6, 0, 5, 8, 9, 6, 7, 7, 1, 4, 7, 6, 7, 1, 4, 5, 7
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OFFSET
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0,1
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COMMENTS
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See the comments to A231983 which will make it clear why on a sphere the solid angle of a square with one degree arc-length side is not exactly one deg^2. The correct value, shown here, is A231983*A231981.
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REFERENCES
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G. V. Brummelen, Heavenly Mathematics: The Forgotten Art of Spherical Trigonometry, Princeton University Press, 2012, ISBN 978-0691148922.
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LINKS
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FORMULA
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4*arcsin(sin(R/2)sin(S/2))*(180/Pi)^2, where R = S = Pi/180.
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EXAMPLE
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0.9999746164392786543219850947849682255179591524185764527406467...
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MATHEMATICA
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RealDigits[4*ArcSin[Sin[Pi/360]^2](180/Pi)^2, 10, 120][[1]] (* Harvey P. Dale, Aug 20 2017 *)
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PROG
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(PARI)
default(realprecision, 120);
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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