SOLUTION: A conical paper cup is to have a height of 4 inches. Find the radius r of the cone that will result in a surface area of 6π in2.

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Question 908334: A conical paper cup is to have a height of 4 inches. Find the radius r of the cone that will result in a surface area of 6π in2.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

 

side surface = +pi%2Ar%2Asqrt%28r%5E2%2Bh%5E2%29

6pi+=+pi%2Ar%2Asqrt%28r%5E2%2B4%5E2%29

6+=+r%2Asqrt%28r%5E2%2B4%5E2%29

(6/r)^2) = r^2 + 16

36/r^2 = r^2 + 16

r^4 + 16r^2 - 36 = 0

(r^2 + 18)(r^2 - 2) = 0, r^2 = 2, r = √2