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A231981
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Decimal expansion of one steradian (sr) expressed in square degrees.
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7
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3, 2, 8, 2, 8, 0, 6, 3, 5, 0, 0, 1, 1, 7, 4, 3, 7, 9, 4, 7, 8, 1, 6, 9, 4, 6, 0, 7, 9, 9, 5, 1, 7, 5, 5, 0, 0, 5, 0, 1, 2, 2, 4, 2, 9, 9, 3, 8, 0, 7, 8, 8, 1, 8, 2, 5, 9, 7, 7, 3, 2, 6, 3, 3, 3, 7, 1, 2, 0, 9, 1, 1, 9, 1, 7, 6, 4, 2, 8, 2, 9, 4, 5, 9, 5, 1, 8, 0, 4, 7, 5, 1, 9, 0, 1, 4, 7, 5, 3, 8, 6, 8, 1, 3, 6
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OFFSET
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4,1
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COMMENTS
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This is the conversion ratio between two solid-angle measures: steradians and square degrees, applicable to integration infinitesimals. The square degree must not be confused with a finite spherical square having one degree side (see A231983, A231984, A231985), just as one steradian must not be confused with the solid angle covered by a spherical square with a side arc-length of one radian (see A231986, A231987).
Equals also full solid angle expressed in degrees, divided by 4*Pi (i.e., A125560/(4*Pi)).
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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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(180/Pi)^2.
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EXAMPLE
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3282.80635001174379478169460799517550050122429938078818259773...
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MATHEMATICA
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RealDigits[(180/Pi)^2, 10, 120][[1]] (* Harvey P. Dale, Nov 23 2019 *)
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CROSSREFS
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Cf. A000796 (Pi), A125560 (full solid angle), A072097 (rad/deg), A019685 (deg/rad), A231982 (inverse, deg^2/sr), A231983 (square with 1 deg side, in sr), A231984 (square with 1 deg side, in square degrees), A231985, A231986 (square with 1 rad side, in sr), A231987.
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KEYWORD
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AUTHOR
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STATUS
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approved
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