Laplace Transform

Question

Compute the following Laplace Transform:

Answer 1

(cost)⁴ = 3/8 + 1/2cos2t + 1/8cos(4t). We get this by using reducting power formula cos²t = (1 + cos2t)/2.

L{(cost)⁴} = 3/8t) = s/(2(s² + 4)) + s/(8(s² + 16))