Help Please

like this

$sin\theta =\frac{e^{i\theta}-e^{-i\theta}}{2i}\\~\\ RHS=\frac{[cos\theta+isin\theta]-[cos(-\theta)+isin(-\theta)]}{2i}\\ RHS=\frac{[cos\theta+isin\theta]-[cos(\theta)-isin(\theta)]}{2i}\\ RHS=\frac{2isin\theta}{2i}\\ RHS=sin\theta\\~\\ RHS=LHS \qquad \qquad Q.E.D.$