# Some assistance needed.

1. Nov 28, 2003

### Superman89

I need help with this word problem.

What is the radius of a circle whose area is 154 square centimeters?
I know i'm suppost to use the formula $A={\pi}r^2$.
What do I need to do next?

2. Nov 29, 2003

### phi1978

You know that $$A$$ (the area) is 154 (square centimetres) so its merely a case of substituting $$A=154$$ into the formula and solving for r (given that $${\pi}$$ is a known value).

3. Nov 30, 2003

### ceptimus

154 = &pi; r^2

r^2 = 154 / &pi;

r = sqrt(154 / &pi;)

r = sqrt(7 * 154 / 22) [as &pi; = 22 / 7 (approximately)]

r = sqrt(7 * 7)

r = 7cm