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A233528
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Decimal expansion of arctan(2*Pi): adjacent angle for a right triangle of equal area to a disk.
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2
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1, 4, 1, 2, 9, 6, 5, 1, 3, 6, 5, 0, 6, 7, 3, 7, 7, 5, 9, 0, 6, 3, 7, 1, 2, 9, 4, 9, 8, 5, 6, 9, 3, 2, 5, 1, 8, 4, 9, 3, 5, 1, 3, 4, 5, 9, 0, 8, 8, 5, 0, 1, 8, 5, 0, 0, 7, 1, 9, 1, 4, 3, 2, 8, 9, 4, 0, 0, 8, 6, 0, 8, 3, 5, 7, 7, 9, 2, 2, 3, 9, 0, 1, 5, 3, 4, 3, 0, 2, 7, 3, 2, 3, 0, 2, 5, 5, 3, 9, 3
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OFFSET
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1,2
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COMMENTS
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In radians, this constant is the arctan(base / height) = arctan(Adjacent / Opposite) = arctan(circumference / radius) for a unit circle is arctan(A019692), where A019692 = 2*A000796.
"Archimedes used the tools of Euclidean geometry to show that the area inside a circle is equal to that of a right triangle whose base has the length of the circle's circumference and whose height equals the circle's radius in his book Measurement of a Circle." quote from Wikipedia link.
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LINKS
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FORMULA
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EXAMPLE
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1.412965136506737759063712949856932518493513459088501850071914328940...
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MATHEMATICA
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RealDigits[ArcTan[2 Pi], 10, 110][[1]] (* Bruno Berselli, Dec 16 2013 *)
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PROG
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(PARI) atan(2*Pi)
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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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