-506 Appendix A Solutions t o the Exercises Solution 11.8 X(:pj (T )= 27r W = iLL Fourier series: 77 S(w - 27rk) k X ( J W )= A,,elTop'" P ( h c a u s r of t h e selectivc property of thc inipulsc at w = 0) Solution 11.9 a) Z(t) I = si(7rt) si(7rt)