SOLUTION: I have this math problem. The area of a circle is 25 square meters. Find the radius of the circle. What I don't understand is how to solve for r, and the answer has numbers to t

Algebra ->  Circles -> SOLUTION: I have this math problem. The area of a circle is 25 square meters. Find the radius of the circle. What I don't understand is how to solve for r, and the answer has numbers to t      Log On


   

Question 50936This question is from textbook Algebra 1 - Saxon
: I have this math problem. The area of a circle is 25 square meters. Find the radius of the circle. What I don't understand is how to solve for r, and the answer has numbers to the hundredth place... This question is from textbook Algebra 1 - Saxon

Found 2 solutions by Earlsdon, tutorcecilia:
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Remember that the area of a circle is given by:
A+=+%28pi%29r%5E2 To solve for r (radius), divide both sides by %28pi%29
A%2F%28pi%29+=+r%5E2 Now take the square root of both sides.
sqrt%28A%2F%28pi%29%29+=+r
If A = 25 sq. meters, and %28pi%29 = 3.14 (Approximately)
r+=+sqrt%2825%2F3.14%29
r+=+2.821meters, rounded to the nearest thousandth.

Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
Area of a circle = (pi)(r^2) [The formula for the area of a circle]
25m^2=(pi)(r^2) [Plug-in the values]
25/pi=(pi)(r^2)/(pi) [Solve for the radius (r)]
25/pi=r^2
%28sqrt%2825%2Fpi%29%29=%28sqrt%28r%5E2%29%29+%29
2.820947=r [Round to the nearest 100th place]
2.82=r
.
Check that (r=2.82) by plugging it back into the original equation:
Area of a circle = (pi)(r^2)
25=(pi)(2.82^2)
25 is equivelent to 24.9832 [Close enough]