Cos^4x

Cos^4x

Input
cos^4(x)
Roots
x = pi n – pi/2, n element Z
Series expansion at x=0
1 – 2 x^2 + (5 x^4)/3 + O(x^6)
(Taylor series)
Derivative
d/dx(cos^4(x)) = -4 sin(x) cos^3(x)
Indefinite integral
integral cos^4(x) dx = 1/32 (12 x + 8 sin(2 x) + sin(4 x)) + constant
Definite integral over a half-period
integral_0^pi cos^4(x) dx = (3 pi)/8~~1.1781
Definite integral over a period
integral_0^(2 pi) cos^4(x) dx = (3 pi)/4~~2.35619
Definite integral mean square
integral_0^(2 pi) (cos^8(x))/(2 pi) dx = 35/128~~0.273438
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