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    hi, i come across this question but totally have no clue to this one. please give me some hints. thanks


    http://www.badongo.com/pic/12781970
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    (Original post by kingsclub)
    hi, i come across this question but totally have no clue to this one. please give me some hints. thanks


    http://www.badongo.com/pic/12781970
    Ok, how much do you know about parametric equations and volumes of revoultion?

    You'll need to convert the two parametric equations into one Cartesian equation in the form y=....
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    so far i've only learnt how to find volumes of a single equation using disc and shell methods...
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    (Original post by kingsclub)
    so far i've only learnt how to find volumes of a single equation using disc and shell methods...
    I've never heard of those methods...

    If you don't know about parametric equations, then I don't think you'll be able to do this. I'm not entirely sure, though.

    (Original post by Farhan.Hanif93)
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    Help? :puppyeyes:
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    (Original post by Doughnuts!!)
    Help? :puppyeyes:
    Somehow, I've never come across integrating the parametric equation of any curve in maths before but I'll try my best.

    (Original post by kingsclub)
    hi, i come across this question but totally have no clue to this one. please give me some hints. thanks


    http://www.badongo.com/pic/12781970
    Have you ever come across the formula for the volume generated by rotating a section of a curve (in cartesian form) completely about the x-axis? I think it'd be similar to dealing with that but instead you'll need to consider:

    V=\pi \displaystyle\int ^{\frac{\pi}{3}}_{-\frac{\pi}{3}} \left(y^2 \dfrac{dx}{dt}\right)dt

    Someone more knowledgeable, feel free to correct me if I'm wrong on this.
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    As Farhan.Hanif93 said.

    Alternatively, eliminate t from your two equations, then get an expression for y^2 from that. You'll need to sort out the limits.

    Edit: Actually, my latter suggestion looks rather messy when I look at the details.
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    (Original post by Farhan.Hanif93)
    Somehow, I've never come across integrating the parametric equation of any curve in maths before but I'll try my best.
    Same. Though I think my hunch about integrating the Cartesian seems to be spot on... :beard:
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    (Original post by Doughnuts!!)
    Same. Though I think my hunch about integrating the Cartesian seems to be spot on... :beard:
    Yeah it should work but, as Ghostwalker says, it will probably get messy. :p:
 
 
 
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