Answer
$w\cdot z$
= $36(cos130^\circ + isin130^\circ)$
Work Step by Step
$w = 12(cos80^\circ + isin80^\circ) = 12cis80^\circ$
$z = 3(cos50^\circ + isin50^\circ) = 3cis50^\circ$
Now, $w\cdot z$
= $12cis80^\circ \cdot 3cis50^\circ$
= $12 \cdot 3 \cdot cis(80^\circ+ 50^\circ)$ (Product Theorem)
= $36cis130^\circ$
= $36(cos130^\circ + isin130^\circ)$
