- I understand that (from the Argand Diagram). Is there an algebraic way to show that ?

- Why is the principal value of the argument taken to be between and ? I was asked to find the modulus and argument of . Here is what I did:

. Right.

. Obviously that isn't between & . What am I supposed to do then?

PS. For the last part (as noticed by Archie Meade), I meant: .