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A137914
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Decimal expansion of arccos(1/3).
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4
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1, 2, 3, 0, 9, 5, 9, 4, 1, 7, 3, 4, 0, 7, 7, 4, 6, 8, 2, 1, 3, 4, 9, 2, 9, 1, 7, 8, 2, 4, 7, 9, 8, 7, 3, 7, 5, 7, 1, 0, 3, 4, 0, 0, 0, 9, 3, 5, 5, 0, 9, 4, 8, 3, 9, 0, 5, 5, 5, 4, 8, 3, 3, 3, 6, 6, 3, 9, 9, 2, 3, 1, 4, 4, 7, 8, 2, 5, 6, 0, 8, 7, 8, 5, 3, 2, 5, 1, 6, 2, 0, 1, 7, 0, 8, 6, 0, 9, 2, 1, 1, 3, 8, 9, 4
(list; constant; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Dihedral angle in radians of regular tetrahedron.
Arccos(1/3) is the central angle of a cube, made by the center and two neighboring vertices. [From Clark Kimberling (ck6(AT)evansville.edu), Feb 10 2009]
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LINKS
| Jackson, Frank and Weisstein, Eric W., Tetrahedron
Weisstein, Eric W., Dihedral Angle
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FORMULA
| arccos(1/3) = arctan(2*sqrt(2)) = 2*arcsin(sqrt(3)/3) = arcsin(2*sqrt(2)/3).
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EXAMPLE
| 1.2309594173407746821349291782479873757103400093550948390555483336639923144...
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PROG
| (PARI) acos(1/3)
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CROSSREFS
| Cf. A137915 (same in degrees).
Sequence in context: A020823 A021437 A074760 * A098989 A175315 A180186
Adjacent sequences: A137911 A137912 A137913 * A137915 A137916 A137917
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KEYWORD
| cons,nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), Feb 22 2008
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