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Homework Help: Finding Surface Area

  1. Feb 8, 2010 #1
    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=[tex]\int[/tex]2[tex]\pi[/tex]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. jcsd
  3. Feb 9, 2010 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Hi danielatha4! :smile:

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