SOLUTION: if the altitude of a right cylinder is doubled, what happens to its surface area?

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Question 477800: if the altitude of a right cylinder is doubled, what happens to its surface area?
Answer by Alan3354(69443) About Me  (Show Source):
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if the altitude of a right cylinder is doubled, what happens to its surface area?
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The SA of a cylinder of height h and radius r is
SA+=+pi%2Ar%2As where s = slant height
s+=+sqrt%28r%5E2+%2B+h%5E2%29
--> SA+=+pi%2Ar%2Asqrt%28r%5E2+%2B+h%5E2%29
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If h is doubled:
--> pi%2Ar%2Asqrt%28r%5E2+%2B+4h%5E2%29
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The ratio is
sqrt%28r%5E2+%2B+4h%5E2%29%2Fsqrt%28r%5E2+%2B+h%5E2%29
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The difference is sqrt%28r%5E2+%2B+4h%5E2%29+-+sqrt%28r%5E2+%2B+h%5E2%29
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Neither the ratio nor the difference makes it obvious.
If both the height and the radius are doubled, the SA is x4 (and the volume is x8).
If one is doubled, the ratio is less than 4 and more than 2, but a quantitative answer depends on the values of r and h, or at least the ratio of r to h.
If h were given to be equal to r and then doubled, a more definitive answer could be obtained.