If z=cosθ+isinθz = \cos\theta + i\sin\thetaz=cosθ+isinθ, find z−1z^{-1}z−1.
cosθ−isinθ\cos\theta - i\sin\thetacosθ−isinθ
cos(−θ)+isin(−θ)\cos(-\theta) + i\sin(-\theta)cos(−θ)+isin(−θ)
Both (a) and (b)
−cosθ−isinθ-\cos\theta - i\sin\theta−cosθ−isinθ