Question

I need help with mat equation

Answer 1

`\qquad \textit{power of a complex number} \\\\\ [\quad r[cos(\theta)+isin(\theta)]\quad ]^n\implies r^n[cos(n\cdot \theta)+isin(n\cdot \theta)] \\\\[-0.35em] ~\dotfill\\\\ z=2[\cos(104^o)~~ + ~~i\sin(104^o)] \\\\\\ z^2=2^2[\cos(2\cdot 104^o)~~ + ~~i\sin(2\cdot 104^o)] \\\\\\ z^2=\underset{polar}{4[\cos(208^o)~~ + ~~i\sin(208^o)]}~\hfill \implies ~\hfill z^2\approx \underset{rectangular}{\stackrel{4\cos(208^o)}{-3.532}~~,~~\stackrel{4\sin(208^o)}{-1.878} i}`