Solution:

Given:

$\begin{aligned} a &=\cos \alpha+i \sin \alpha \\\\ b &=\cos \beta+i \sin \beta \\\\ \& c & =\cos \gamma+i \sin \gamma \end{aligned}\\ $

Now,

$\frac{\mathrm{ab}}{\mathrm{c}}=\mathrm{ab}(\mathrm{c})^{-1}\\ $

$=(\cos \alpha+i \sin \alpha)(\cos \beta+i \sin \beta)(\cos \gamma+i \sin \gamma)^{-1}\\ $

$ =(\cos \alpha+i \sin \alpha)(\cos \beta+i \sin \beta)(\cos \gamma-i …