Answer
The rectangular form of the complex number is $6+6\sqrt{3}i$.
Work Step by Step
Here
$\begin{align}
& z=12\left( \cos 60{}^\circ +i\sin 60{}^\circ \right) \\
& =x+iy
\end{align}$
Therefore, $x=12\cos 60{}^\circ,y=12\sin 60{}^\circ $
Simplify it further to get,
$\begin{align}
& x=12\times \left( \frac{1}{2} \right) \\
& =6 \\
& y=12\times \left( \frac{\sqrt{3}}{2} \right) \\
& =6\sqrt{3}
\end{align}$
So, the rectangular form of the complex number is $6+6\sqrt{3}i$
