SOLUTION: 25 meters and {{{I have looked to see if I can get help and do not see this anywhere. I am lost for this one. Crop circles. The expression πr2 gives the area of a circle wi

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: 25 meters and {{{I have looked to see if I can get help and do not see this anywhere. I am lost for this one. Crop circles. The expression πr2 gives the area of a circle wi      Log On

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Question 354211: 25 meters and 25+meters+and+I have looked to see if I can get help and do not see this anywhere. I am lost for this one.
Crop circles. The expression πr2 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 Southwind Ranch?

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Start with the formula for the area of a circle:
A+=+%28pi%29r%5E2 but you want this in terms of the diameter, and r+=+D%2F2, so...
A+=+%28pi%29%28D%2F2%29%5E2 Substitute D = 25 meters and pi+=+3.14 as an approximation.
A+=+%283.14%29%2825%2F2%29%5E2 evaluate.
A+=+3.14%28625%2F4%29
A+=+3.14%28156.25%29
highlight%28A+=+490.625%29 square meters.