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A019857 Decimal expansion of sine of 48 degrees.

%I A019857 #29 Aug 31 2025 11:22:42
%S A019857 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,
%T A019857 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,
%U A019857 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
%N A019857 Decimal expansion of sine of 48 degrees.
%C A019857 An algebraic number of degree 8 and denominator 2. - _Charles R Greathouse IV_, Aug 27 2017
%H A019857 Ivan Panchenko, <a href="/A019857/b019857.txt">Table of n, a(n) for n = 0..1000</a>
%H A019857 Wikipedia, <a href="http://en.wikipedia.org/wiki/Exact_trigonometric_constants">Exact trigonometric constants</a>
%H A019857 <a href="/index/Al#algebraic_08">Index entries for algebraic numbers, degree 8</a>
%F A019857 Equals cos(7*pi/30) = 2F1(17/20,3/20;1/2;3/4) / 2. - _R. J. Mathar_, Oct 27 2008
%F A019857 Equals 2*A019833*A019875. - _R. J. Mathar_, Jan 17 2021
%F A019857 Equals 1/(sqrt(5+2*sqrt(5))-sqrt(3)). - _Seiichi Manyama_, Mar 19 2021
%F A019857 4*this^3 -3*this = -A019845. - _R. J. Mathar_, Aug 29 2025
%F A019857 One of the 8 real-valued roots of 256*x^8-448*x^6+224*x^4-32*x^2+1=0. - _R. J. Mathar_, Aug 31 2025
%e A019857 0.74314482...
%t A019857 RealDigits[ Sin[4 Pi/15], 10, 111] (* _Robert G. Wilson v_ *)
%o A019857 (PARI) sin(4*Pi/15) \\ _Charles R Greathouse IV_, Aug 27 2017
%Y A019857 Cf. A019833, A019875.
%K A019857 nonn,cons,changed
%O A019857 0,1
%A A019857 _N. J. A. Sloane_