Question

Express the complex number in trigonometric form.

-2i

Answer 1

easier than it looks
there is no real part, only complex part, so the angle is \(-\frac{\pi}{2}\)

Answer 2

oops
angle is \(-\frac{\pi}{2}\) or if you prefer \(\frac{3\pi}{2}\)

Answer 3

These are my answer choices

2(cos 180° + i sin 180°)

2(cos 90° + i sin 90°)

2(cos 270° + i sin 270°)

2(cos 0° + i sin 0°)

Answer 4

and of course \(r=|-2i|=2\)
you get
\[-2i=2\left(\cos(\frac{3\pi}{2})+i\sin(\frac{3\pi}{2})\right)\]

Answer 5

you are using degrees for this???
ok

Answer 6

yeah degrees. my online teacher makes no sense

Answer 7

convert \(\frac{3\pi}{2}\) to degrees

Answer 8

270?

Answer 9

so this would be the answer?
2(cos 270° + i sin 270°)