(a) Obtain the time-average auto correlation function of x(t) = 3 + 6 cos (20t) + 3...

(a) Obtain the time-average auto correlation function of x(t) = 3 + 6 cos (20πt) + 3 sin (20πt). (Combine the cosine and sine terms into a single cosine with a phase angle.)
(b) Obtain the power spectral density of the signal of part (a). What is its total average power?