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Calc II

  1. Apr 7, 2010 #1
    ?Find the surface area when Y = (a^2 - x^2)^(1/2) is revolved around the x-axis?

    ?Geometrically, what have you found?

    Please help. Thank you.
  2. jcsd
  3. Apr 7, 2010 #2

    Char. Limit

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    Could you show us what you have tried? It might give us an idea on where you need help.

    Also, there is a template for homework posts. For future reference, please use it. It should appear by default whenever you start a new topic in the homework section.
  4. Apr 8, 2010 #3
    I just need help on how to set up the problem. (And i'll definitely use the template next time)
  5. Apr 8, 2010 #4

    Char. Limit

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    Well, firstly, how well do you know arc length? Because it will be needed here...

    And tell me, how would you find the surface area of a regular solid, like say a cylinder, that has no top or bottom to consider?

    Your equation in a more elegant format:

  6. Apr 8, 2010 #5
    Your equation [tex]y=\sqrt{a^2-x^2}[/tex] may be more recognizable in the form [itex]y^2+x^2=a^2[/itex]. What shape does the graph of this equation have? Can you deduce how [tex]y=\sqrt{a^2-x^2}[/tex] relates to [itex]y^2+x^2=a^2[/itex]? This should help with the second question (and also give you an idea of what to expect for the answer to the first question). As Char.Limit pointed out, a good look at the arc length and surface area formulas might be in order.
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