Let e_r=(cos[tex]\theta[/tex],sin[tex]\theta[/tex]) and e_theta=(-sin[tex]\theta[/tex],cos[tex]\theta[/tex]).

Let P(r,[tex]\theta[/tex]) be a point with e_r and e_theta at that point.

What can you say about the three quantities (e_r, e_theta and the point P) as r and [tex]\theta[/tex] vary?

**2. Homework Equations**

r: distance from origin

[tex]\theta[/tex]: angle

**3. The Attempt at a Solution**

As r moves around, the e_r and e_theta change place. As r increases or decreases e_r and e_theta don't change place but as theta changes, they do change place since e_theta is always orthogonal to point P.

I feel like I'm not putting enough information. Is there something i didn't mention?

Thank you.