Rearranging equations to solve for different variable.

Hi,

I've been trying to re-arrange this equation to solve for R instead of A, but I can't seem to get it past being self-referential, and if I assign values to the variables, and recalculate with my re-arrangements, I get different answers, which indicates to me that I'm doing something wrong. Here's the equation:

**A=R/√(R^2+X^2)**

I figure the first step should be:

**A*****√(R^2+X^2)****=R/√(R^2+X^2)*****√(R^2+X^2)**

simplifying to:

**A*****√(R^2+X^2)****=R**

But that is about as far as I can get. How can I get R all on one side of the equation?