Let (a) compute the Fourier cosine coefficients for 9/8 (-cos(4k) 3ksin(k)-cos(k))/(4*k^2) (b) give values for the Fourier cosine series.

a) Determine the coefficients using the given formula.
b) Calculate the values for the Fourier cosine series.
c) Identify the periodicity of the given function.
d) Evaluate the convergence of the Fourier series.