Answer
$$ - 3\sqrt 3 + 3i$$
Work Step by Step
$$\eqalign{
& \left[ {3\left( {\cos {{60}^ \circ } + i\sin {{60}^ \circ }} \right)} \right]\left[ {2\left( {\cos {{90}^ \circ } + i\sin {{90}^ \circ }} \right)} \right] \cr
& {\text{Multiply using the Product Theorem}} \cr
& {\text{ = }}\left( {\text{3}} \right)\left( 2 \right)\left[ {\cos \left( {{{60}^ \circ } + {{90}^ \circ }} \right) + i\sin \left( {{{60}^ \circ } + {{90}^ \circ }} \right)} \right] \cr
& {\text{ = }}6\left( {\cos {{150}^ \circ } + i\sin {{150}^ \circ }} \right) \cr
& {\text{Write in Rectangular form}} \cr
& {\text{ = }}6\left( { - \frac{{\sqrt 3 }}{2} + \frac{1}{2}i} \right) \cr
& = - 3\sqrt 3 + 3i \cr} $$
