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Equals cos(87 degrees) = cos(29*Pi/60) = sin(Pi/60) = sqrt(8-sqrt(3)-sqrt(15)-sqrt(10-2*sqrt(5)))/4 (an intermediate calculation by Dr. Rob - see Math Forum link). - Rick L. Shepherd, Jul 03 2006
EXAMPLE
0.052335956242943832722118629609...
CROSSREFS
Cf. A019896 (cosine of 3 degrees), A019901 (tangent of 3 degrees), A019985 (cotangent of 3 degrees).