A019893 Decimal expansion of sine of 84 degrees.

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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cons
• changed

Comments

Equals sin(7*Pi/15). - Wesley Ivan Hurt, Sep 01 2014

An algebraic number of degree 8 and denominator 2. - Charles R Greathouse IV, Aug 27 2017

Examples

			0.9945218953682733369226919449805703815207920887093194273665588...
		

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..1000
• Wikipedia, Exact trigonometric constants
• Index entries for algebraic numbers, degree 8

Programs

Maple

Digits:=100: evalf(sin(7*Pi/15)); # Wesley Ivan Hurt, Sep 01 2014

Mathematica

RealDigits[ Cos[Pi/30], 10, 111] (* Robert G. Wilson v *)
RealDigits[Sin[84 Degree],10,120][[1]] (* Harvey P. Dale, May 14 2022 *)

PARI

cos(Pi/30) \\ Charles R Greathouse IV, Aug 27 2017

Formula

Equals cos(Pi/30) = 2F1(11/20,9/20;1/2;3/4) / 2. - R. J. Mathar, Oct 27 2008

Equals 2*A019851*A019857. - R. J. Mathar, Jan 17 2021

Satisfies 256*x^8 -448*x^6 +224*x^4 -32*x^2 +1 = 0. - R. J. Mathar, Aug 29 2025

4*this^3 -3*this = A019881. - R. J. Mathar, Aug 29 2025