Answer
$-2-2i\sqrt 3$
Work Step by Step
$\cos 240^{\circ}=-0.5$ and $\sin 240^{\circ}=-\frac{\sqrt 3}{2}$
Substituting these values in the question,
$4(\cos 240^{\circ}+i\sin 240^{\circ})=4(-0.5+i(-\frac{\sqrt 3}{2}))=-2-2i\sqrt 3$
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