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General question about finding area of a solid by rotating axis

  1. Feb 1, 2005 #1
    I just have a general question here. There's this question in the textbook that asks to sketch a graph and then find the volume generated by revolving the region about the x-axis. The three equations they give is y = x, y = 0, x = 1.

    Aren't we suppose to sketch a graph of those three equations? Because in the sols manual, they graph instead, y = x^3 and x + y = 10
  2. jcsd
  3. Feb 1, 2005 #2
    The solutions manual may be for a different edition, because there is no reason to graph the two equations it contains with respect to the original question.
  4. Feb 1, 2005 #3
    Thanks. I thought there was some mathematical reasoning behind graphing those two equations in the manual.
  5. Feb 1, 2005 #4


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    Nevermind the solution.In the original form,the text doesn't make any sense...The volumes considered are either 0 or infinite...

  6. Feb 1, 2005 #5
    Thanks Dan
  7. Feb 1, 2005 #6
    Hi dexter,
    I believe the text is talking about rotating the area contained by those 3 equations, which is a right-triangle with a vertex at the origin.
  8. Feb 2, 2005 #7


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    Indeed, by rotating the region bounded by the three graphs you get a cone of height 1 and radius 1.
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