A387440 Decimal expansion of cos(Pi/11).

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

Offset: 0

Author

R. J. Mathar, Aug 29 2025

Keywords

• nonn
• cons
• new

Examples

			0.95949297361449738989...
		

Links

• R. J. Mathar, Reduction formulas of the cosine of integer fractions of pi, (2008) vixra:2210.0026
• Index entries for algebraic numbers, degree 5

Crossrefs

Cf. A019678.

Formula

Largest of the 5 real-valued roots of 32*x^5 -16*x^4 -32*x^3 +12*x^2 +6*x-1 =0.

Equals sin(9*Pi/22).