P.C.5 The following signal is the product of a sinusoid and a finite Fourier series: x(t)=sin(7t)(k=33 2+jk3ejkt) a. Explain why the term in parentheses is real-valued. b. Use the frequency shifting property to make a sketch of the spectrum of the signal defined above. c. Since the signal x(t) is real, verify that the spectrum is conjugate symmetric..