The formula for finding the area $A$ of a circle is:

$A = \pi r^2$

To solve for the radius $r$, follow these steps:

1. Divide both sides by $\pi$: $\frac{A}{\pi} = r^2$

2. Take the square root of both sides to solve for $r$: $r = \sqrt{\frac{A}{\pi}}$

Thus, the formula for $r$ is:

$r = \sqrt{\frac{A}{\pi}}$

Let me know if you'd like further details or have any questions!

Related Questions:

1. How would the formula change if you had the circumference instead of the area?
2. What is the area of a circle with a radius of 5 cm?
3. How does the area of a circle change if the radius is doubled?
4. Can you solve for the radius when the area is 50 square units?
5. How would the formula apply in 3D to find the radius of a sphere from its surface area?

Tip:

Always ensure that units are consistent when calculating area or radius in geometry problems.