Write the complex number in trigonometric form, using degree measure for the argument.
--5i
A) 5(cos 90° + i sin 90°)
B) 5(cos 0° + i sin 0°)
C) 5(cos 270° + i sin 270°)
D) 5(cos 180° + i sin 180°)

Question

Quizplus · Accepted Answer

The complex number -5i is located on the negative imaginary axis, which corresponds to an angle of 270° in the complex plane. The modulus is 5, so the trigonometric form is 5(cos 270° + i sin 270°).

Write the Complex Number in Trigonometric Form, Using Degree Measure