A: 4, 3:4, (2:5 and a=5, b=5, c=6 5. Answer the following questions. (a) Let f(t) = e\" cos bi. Find {f[t)}. (2 points) (b) Find {f'[t)} using an appropriate formula without computing the derivative f '(t). (1 point) 1 00 ((1) Evaluate the improper integral [a ( 1.2 + 62? dm. [3 points)