# Homework Help: Finding Surface Area

1. Feb 8, 2010

### danielatha4

1. The problem statement, all variables and given/known data
Find the area of the surface obtained by rotating the curve y=1+5x2 from x=0 to x=8 about the y-axis

2. Relevant equations
As=$$\int$$2$$\pi$$g(x)sqrt(1+[g'(x)]2)

3. The attempt at a solution
I changed the limits to suit the y direction, the lower limit becomes 1 and the upper 321. I solved x as a function of y in order to rotate around the y axis and when I plug everything into the formula is becoems a really messy integral I can't solve. I'm sure there's an easier way.

2. Feb 9, 2010

### tiny-tim

Hi danielatha4!

Why not just use ∫ 2πx √(1 + g'(x)2) dx ?