Multiply the Complex Numbers Below and Leave the Result in Trigonometric

Multiple Choice

Multiply the complex numbers below and leave the result in trigonometric form. $\left[ 7 \left( \cos \frac { 6 \pi } { 7 } + i \sin \frac { 6 \pi } { 7 } \right) \right] \left[ 2 \left( \cos \frac { 4 \pi } { 9 } + i \sin \frac { 4 \pi } { 9 } \right) \right]$

A) $9 \left( \cos \frac { 82 \pi } { 63 } + i \sin \frac { 82 \pi } { 63 } \right)$
B) $9 \left( \cos \frac { 10 \pi } { 63 } + i \sin \frac { 10 \pi } { 63 } \right)$
C) $14 \left( \cos \frac { 10 \pi } { 63 } + i \sin \frac { 10 \pi } { 63 } \right)$
D) $14 \left( \cos \frac { 82 \pi } { 63 } + i \sin \frac { 82 \pi } { 63 } \right)$
E) $14 \left( \cos \frac { 58 \pi } { 63 } + i \sin \frac { 58 \pi } { 63 } \right)$