A019857 Decimal expansion of sine of 48 degrees.

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

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• cons
• changed

Comments

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

Examples

			0.74314482...
		

Links

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

Crossrefs

Cf. A019833, A019875.

Programs

Mathematica

RealDigits[ Sin[4 Pi/15], 10, 111] (* Robert G. Wilson v *)

PARI

sin(4*Pi/15) \\ Charles R Greathouse IV, Aug 27 2017

Formula

Equals cos(7*pi/30) = 2F1(17/20,3/20;1/2;3/4) / 2. - R. J. Mathar, Oct 27 2008

Equals 2*A019833*A019875. - R. J. Mathar, Jan 17 2021

Equals 1/(sqrt(5+2*sqrt(5))-sqrt(3)). - Seiichi Manyama, Mar 19 2021

4*this^3 -3*this = -A019845. - R. J. Mathar, Aug 29 2025