SOLUTION: If you double the height and radius of a cylinder, why doesn't the surface area double? Thanks!

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Question 699630: If you double the height and radius of a cylinder, why doesn't the surface area double? Thanks!
Found 2 solutions by htmentor, lwsshak3:
Answer by htmentor(1343) About Me  (Show Source):
You can put this solution on YOUR website!
Surface area of a cylinder
S=2%2Api%2Ar%2Ah
Doubling both the radius, r and the height, h gives
S=2%2Api%2A2r%2A2h
So the new surface area is four times the old surface area

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
If you double the height and radius of a cylinder, why doesn't the surface area double?
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Because the surface area of the top and bottom varies as the square of the radius, that is, if you double the radius, the surface areas of the top and bottom increase 4 times. Area=πr^2