4 Find and sketch the Fourier transforms for the following signals. u(t)=(1-|t|) I_{[-1,1]}(t) v(t)=\operatorname{sinc}(2 t) \operatorname{sinc}(4 t) \text {. } \text { (c) } s(t)=v(t) \cos (200 \pi t) \text

{. } (d) Classify cach of the signals in (a) (c) as baseband or passband.