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Math Help - bits n bobs

  1. #1
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    bits n bobs

    few little grey areas:

    1) how would i work this one out:

    find the vloume generated by rotationg the area bounded by y=x^2 and y=4 around the line y=1
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  2. #2
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    It is the same as rotating (x+1)^2 around y=0. Use the volume of rotation formula.
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  3. #3
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    Quote Originally Posted by ThePerfectHacker View Post
    It is the same as rotating (x+1)^2 around y=0. Use the volume of rotation formula.

    what formula is that?
    x
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  4. #4
    Super Member Rebesques's Avatar
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    \int_a^b \pi f^2(x)dx.
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  5. #5
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    Quote Originally Posted by Rebesques View Post
    \int_a^b \pi f^2(x)dx.
    It should be,
    2\pi \int_a^b xf(x) dx
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  6. #6
    Super Member Rebesques's Avatar
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    I doubt it

    This random page says otherwise:

    Volume of A Solid of Revolution


    Are you talking about surface area maybe?
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