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Homework Help: Surface Area about x axis

  1. Apr 13, 2013 #1
    1. The problem statement, all variables and given/known data
    x^2 + (y - 2)^2 = 1
    The hint given by the question was to split the function into 2

    2. Relevant equations
    Surface Area about x axis

    3. The attempt at a solution
    So i did this.
    (y - 2)^2 = 1 - x^2
    y = √(1 - x^2) +2 and y = 2 - √(1 - x^2)

    The range I calculated
    when y= 0; x = - √(-3) and x = √(-3)

    I use the formula ∫ 2∏ * (√(1-x^2) + 2)√(1 + x^2/(1 - x^2))dx

    Then i got stuck as it became messy
  2. jcsd
  3. Apr 13, 2013 #2


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    2017 Award

    Staff: Mentor

    That just means that y=0 does not happen. Your integration limits are determined by something else...
    How did you get that formula?
  4. Apr 13, 2013 #3


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    Science Advisor
    Homework Helper
    Gold Member

    The first step would be to identify the curve that is being rotated. Have you drawn its graph? Do you see why you would want to use the hint?
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