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Math Help - Math C Question on 'Volumes of Revolution'

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    Math C Question on 'Volumes of Revolution'

    Ok so I have the two coordinates (0,3) and (2,7)
    The line that runs through them is y=2x+3
    How do I find the volume created by rotating the line around the x axis..
    In other words, I will be using volumes of revolution.

    However, I have only bee taught on this how to just find the volume of a straight line only using one coordinate. Would it work the same or would I need to use both coordinates? Would the limits be from 0 to 7? and then intergrating 4x^2+12x+9 and multiplying it by pie?

    Many thanks to those who reply
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    Re: Math C Question on 'Volumes of Revolution'

    Quote Originally Posted by BryannaAllan View Post
    Ok so I have the two coordinates (0,3) and (2,7)
    The line that runs through them is y=2x+3
    How do I find the volume created by rotating the line around the x axis..
    In other words, I will be using volumes of revolution.
    If you want to use calculus then
    \int_0^2 {2\pi {r^2}dx} where r=(2x+3).

    However, simple algebra will work. It is the difference of the volumes of two cones.
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