Question

Express the complex number in trigonometric form.

-5i

Answer 1

Show your best guess and I'll help you along.

Answer 2

\[re^{i \theta}=r ( \cos \theta + i \sin \theta)\]

Answer 3

ok 5(cos 180° + i sin 180°)

Answer 4

No, because if you calculate cos(180)=-1 and sin(180)=0

Answer 5

So you'll get -5 instead of -5i which is what you want. You need to have the cosine (real) part be zero and the sine(imaginary) part be -1.