I'm new on the site and have a question that I feel is pretty basic, but I can't seem to get it right.

I'm given a vector of the form

**A =**(x

**x**-y

**y**). The mathematical paper I'm reading does a quick conversion to polar coordinates and the result is

**A**=r

**(Theta)**, where (theta) is the unit vector in the theta direction.

I've read wikipedia's page and several links on converting between the coordinates and many of them go into the math of finding r and finding theta, but none of them show how to assign these values in unit vector notation. I don't understand why the r for the vector above ended up in the

**Theta**direction and why the

**r**direction is zero. Could anyone please help?

Thank you.