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Homework Help: Volume and surface area of the sphere using integration

  1. Sep 15, 2010 #1
    1. The problem statement, all variables and given/known data

    i was trying to find the surface area of the sphere using integration, ( by revolving circle on the x axis )

    the thing is it doesn't work as the volume problem. i mean in volume problem to get the volume of the sphere, you would start with circle and start slice it into little pieces, then you would multiply the area of that slice with the thickness which is dx

    but in the surface problem you would multiply the circumference of the slice with the incremental arch Length which is ds

    why i cannot in the surface problem multiply the circumference by the thickness dx, and i have to multiply it by the arc length ds

    actually i uploaded a pdf file to clarify things

    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Sep 16, 2010 #2
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