SOLUTION: I need help with this question: The expression Pi r^2 gives the area of a circle with radius r. How many square meters of wheat were destroyed when an alien ship made a crop cir

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Question 44787: I need help with this question:
The expression Pi r^2 gives the area of a circle with radius r. How many square meters of wheat were destroyed when an alien ship made a crop circle of diameter 25 meters in the wheat field at the Southwest Ranch?
Found 2 solutions by Nate, Chris435435:
Answer by Nate(3500) About Me  (Show Source):
You can put this solution on YOUR website!
2r = d
2r = 25
r = 25/2 = 12.5
AREA+=+%28pi%29r%5E2
AREA+=+%28pi%29%2812.5%29%5E2
About 491 square meters....

Answer by Chris435435(8) About Me  (Show Source):
You can put this solution on YOUR website!
They gave you the diameter of the circle in the question. The diameter of a circle is equivalent to twice its radius. That is: d=2r. We know from the question that the diameter of this crop circle is 25 meters. So let's plug that in to the formula and that'll give us the radius of the circle.
25=2r
r=25%2F2
r=12.5
Now that we know the radius, which is 12.5 meters. Let's plug that into the formula for the area of the circle to get our answer:
A=pi%2A%2812.5%29%5E2
A=490.87
You also could compute 12.5%5E2 and leave pi alone. In that case,
A=156.25pi