Multiply the complex numbers below and leave the result in trigonometric form.
B)
C)
D)

Question

Multiply the complex numbers below and leave the result in trigonometric form. ​ 
B)​ 
C)​ 
D)​

Quizplus · Accepted Answer

To multiply complex numbers in trigonometric form, we simply multiply the magnitudes and add the angles. 
11e^(iπ/2) * e^(iπ/2) = 11*e^(iπ/2 + iπ/2) = 11*e^(iπ) = 11*(-1) = -11
The resulting magnitude is 11 and the angle is π, which is equivalent to adding π to the initial angle of π/2. Therefore, the answer in trigonometric form is 11e^(i3π/2) or 11e^(-iπ/2). 
Choice C has the correct magnitude and angle, so it is the best choice.

Multiply the Complex Numbers Below and Leave the Result in Trigonometric