A019875 Decimal expansion of sine of 66 degrees.

9, 1, 3, 5, 4, 5, 4, 5, 7, 6, 4, 2, 6, 0, 0, 8, 9, 5, 5, 0, 2, 1, 2, 7, 5, 7, 1, 9, 8, 5, 3, 1, 7, 1, 7, 7, 9, 4, 0, 8, 1, 0, 4, 5, 9, 3, 7, 7, 4, 7, 4, 5, 4, 5, 0, 6, 0, 9, 9, 9, 7, 8, 8, 0, 6, 5, 1, 1, 4, 8, 8, 2, 1, 0, 2, 6, 3, 1, 2, 7, 1, 6, 8, 1, 7, 8, 4, 0, 0, 0, 8, 9, 3, 2, 9, 9, 9, 9, 4

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cons

Comments

A quartic number with denominator 2. - Charles R Greathouse IV, Aug 27 2017

Examples

			0.913545457...
		

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..1000
• Wikipedia, Exact trigonometric constants
• Index entries for algebraic numbers, degree 4

Crossrefs

Cf. A019821, A019842, A019866, A019887.

Programs

Mathematica

RealDigits[N[Cos[2*Pi/15], 110]][[1]] (* Wesley Ivan Hurt, Dec 27 2021 *)

PARI

cos(2*Pi/15) \\ Charles R Greathouse IV, Aug 27 2017

Formula

Equals cos(2*Pi/15) = 2*A019887^2 - 1 = 1 - 2*A019821^2. - R. J. Mathar, Jun 18 2006

Equals 2*A019842*A019866. - R. J. Mathar, Jan 17 2021