Posted by **Kenya** on Wednesday, May 14, 2008 at 11:20pm.

How do you do these problems???

What is the radius of a circle that its area is 254.5 square inches???

What is the diameter of a circle if its area is 132.7 square meters??

I don't understand this because of the thing that says "square"

- Adv. Math -
**Reiny**, Thursday, May 15, 2008 at 12:08am
area of circle = pi(r^2)

so for the first one :

254.5 = pi(r^2), divide both sides by pi

81 = r^2 , now take the square root of both sides

9 = r

do the second one the same way, double the answer you get for r to get the diameter.

- Adv. Math -
**Ms. Sue**, Thursday, May 15, 2008 at 11:27am
For an explanation of "square" in a circle, check this site.

http://www.mathgoodies.com/lessons/vol2/circle_area.html

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