Define angle from polar vector?

Hello

Once again a silly interface question: I have a vector in polar form. Now I could easily write down the real and the imaginary values down go on from there but I want to be able to define the angle of the vector so that I can use that angle later on. However I can not find a MathCad feature or some neat trick to get that angle defined. I have attached a picture with an example to show you what I mean.

I hope one of you have a neat solution. I use MathCad 3.1 by the way.

Best regards
Emil