## Introductory Algebra for College Students (7th Edition)

Substitute the given area and solve for r. $A=\pi r^2$ Substitute the area for A. $36\pi=\pi r^2$ Divide both sides by $\pi$. $36\pi \div \pi=\pi r^2\div \pi$ Simplify. $36=r^2$ Take the square root of each side. $\sqrt{36}=\sqrt{r^2}$ Simplify. $6=r$