Some assistance needed.

[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?

[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).

[ceptimus]

154 = π r^2

r^2 = 154 / π

r = sqrt(154 / π)

r = sqrt(7 * 154 / 22) [as π = 22 / 7 (approximately)]

r = sqrt(7 * 7)

r = 7cm