Adv. Math
posted by Kenya on .
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"

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. 
For an explanation of "square" in a circle, check this site.
http://www.mathgoodies.com/lessons/vol2/circle_area.html