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# surface area of revolution watch

1. find the area of the surface obtained by revolving the curve y=x^2, 0<x<1 about the y axis
2. use the formula attached:
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3. y = x^2 => x = y^1/2

x = 0, y = 0, x = 1, y = 1

Surface area, S = 2*pi*integral [0, 1] of g(y)(1 + [g'(y)]^2)^1/2

g(y) = y^1/2
g'(y) = (1/2)y^-1/2

[0,1] are the limits.

You should be able to do it from there.
4. (Original post by elpaw)
use the formula attached:
Damn you elpaw!
5. thanx u guys
6. (Original post by Simbo)
thanx u guys
sorry, i didnt see te "about y axis". The formula for your case is thus....
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