Use the time-shifting property to find the inverse transforms of the following functions:

(a) \(F_{1}(\omega)=[6 \pi \delta(\omega) j 6 / \omega] e^{-j 5 \omega}\)

(b) \(F_{2}(\omega)=50 e^{-j 4 \omega} /(j \omega+5)\)

(c) \(F_{3}(\omega)=2 \cos (20 \omega) / j \omega\)