(a) $\frac{\cos{30{^\circ} + i\sin{30{^\circ}}}}{\cos{60{^\circ} - i\sin{60{^\circ}}}}$ $= \left( \cos{30{^\circ} + i\sin{30{^\circ}}} \right)(\cos{60{^\circ} + i\sin{60{^\circ}}})$ $= \cos{90{^\circ} + i\sin{90{^\circ} = i}}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.