What is the radius of a circle with an area of 154 square centimeters?

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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?
 
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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).
 
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
 

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