Question

Express the complex number in trigonometric form.

-4

Answer 1

So, do you know how to find the the angle?

Answer 2

Try to think of the unitcircle

Answer 3

-4 is simply just a scaled-up -1 so that means that the angle is what?

Answer 4

180 degrees?

Answer 5

@frx

Answer 6

Exactly

Answer 7

Or pi since you're looking for the polarform

Answer 8

Thanks. These are the possible answers:
4(cos 270° + i sin 270°)

4(cos 90° + i sin 90°)

4(cos 0° + i sin 0°)

4(cos 180° + i sin 180°)

So how do I find out which one of those is the answer if it is pi or 180 degrees? thanks again

Answer 9

\[|z|=\sqrt{4^{2}}=4\]
\[\arg(z)= \pi \]
\[4(\cos \pi+isin \pi)\]

Answer 10

So since your alternatives are in degrees and not radians you know it's 180 degrees.

Answer 11

So it's the last one of your options

Answer 12

Oh i see what you did. Thank you so much man. I really appreciate your help. Very thorough explanation.

Answer 13

No problem :)

Answer 14

If you have any questions just send a pm