Convert the following instantaneous currents to phasors, using \(\cos (\omega t)\) as the reference. Give your answers in both rectangular and polar form.

(a) \(i(t)=400 \sqrt{2} \cos \left(\omega t-30^{\circ}\right)\);

(b) \(i(t)=5 \sin \left(\omega t+15^{\circ}\right)\);

(c) \(i(t)=4 \cos \left(\omega t-30^{\circ}\right)+5 \sqrt{2} \sin \left(\omega t+15^{\circ}\right)\).