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Homework Help: Surface area of a cone

  1. Feb 5, 2012 #1
    1. The problem statement, all variables and given/known data


    I understand everything except for the part where the -1 pops out of nowhere on step 4. why? how?
  2. jcsd
  3. Feb 5, 2012 #2


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    Homework Helper

    Remember that when you solve an integral, you need to take the integral of the highest value minus lowest value. So if you want to solve


    Then you'll have


  4. Feb 5, 2012 #3


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    Gold Member

    the 1 is the result of substituting the lower limit of the previous step, ie x = 0, which subtracted from the upper limite of the previous step, x = 1/2

    edit: oops. too late
  5. Feb 5, 2012 #4
    thanks, I got it.
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