A019866 -id:A019866 - cp's OEIS frontend

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

N. J. A. Sloane

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

			0.913545457...

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

Cf. A019821, A019842, A019866, A019887.

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

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

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
Largest of the 4 real-valued roots of 16*x^4-8*x^3-16*x^2+8*x+1=0. (Other A019851, -A019815, -A019887). - R. J. Mathar, Sep 04 2025

A019955 Decimal expansion of tangent of 57 degrees.

Original entry on oeis.org

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

Offset: 1

N. J. A. Sloane

Also the decimal expansion of cotangent of 33 degrees. - Ivan Panchenko, Sep 01 2014

			1.5398649638145829048267969726027801257083870321654816797991855...

Ivan Panchenko, Table of n, a(n) for n = 1..1000
Wikipedia, Exact trigonometric constants

Cf. A019866 (sine of 56 degrees).

SetDefaultRealField(RealField(100)); R:= RealField(); Tan(19*Pi(R)/60); // G. C. Greubel, Nov 22 2018

RealDigits[Tan[57 Degree],10,120][[1]] (* Harvey P. Dale, Jul 20 2016 *)
RealDigits[Tan[19*Pi/60], 10, 100][[1]] (* G. C. Greubel, Nov 22 2018 *)

default(realprecision, 100); tan(19*Pi/60) \\ G. C. Greubel, Nov 22 2018

numerical_approx(tan(19*pi/60), digits=100) # G. C. Greubel, Nov 22 2018

Equals cot(11*Pi/90) = (1/4)*(2 - sqrt(2*(5 - sqrt(5))))*(2 - (2 + sqrt(3))*(3 + sqrt(5))). - G. C. Greubel, Nov 22 2018

cp's OEIS Frontend

A019875 Decimal expansion of sine of 66 degrees.

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