3.3 Exercises 59 Exercise 3.1 Rwognisr t hti friqucncics of- t I-re following signals in the complex fr equeiicy plane J(,( I) l'?,(t) (t) + - r -2t ( I sin t ) A COSUl(]/ + H cos Zw,$ = sin(w,l -tp) = xercisc? 3.2 13 - ??? - ??? siri( ~t )l 4sin(I (It) c 5cos(LVlt t 20") 6- C O S ( 51 )