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Pleaaaase help me

  1. Dec 2, 2004 #1
    this is my first post,and I hope i get the help I need;)
    equation of curve 2y^2=x^3 find the volume of the solid formed by the complete rotation about the y axis of the region bounded by the curve the y azis and the line with the equation y=2 which lies in the first quadrant,*done this*
    npw i need help in second part of the question
    find also the volume formed when the region is rotated completely about the x axis
    I also have a question would anyone help me and explain what shall we do if the rotation was not 360 about the x axis,but was 180
    thanx in advance:D
  2. jcsd
  3. Dec 2, 2004 #2


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    Rotating about the x axis is mathematically equivalent to swapping x and y in the relation given then rotating about the y axis so that whatever method you used in the first problem should work for the second problem.

    Also, rotating halfway will give you half the volume of a full rotation.
  4. Dec 2, 2004 #3
    well that is what driving me crazy,because in the second one I tried to make the equation with the y as a subject then squared it and substituted with 2 but it didn't work the answer was wrong:(
  5. Dec 2, 2004 #4


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    suggestion: curiosity is more powerful an attraction than academic pity. try stating the problem next time in the title. your current title has been used a lot before, and to me personally is often reason enough to ignore the post.
  6. Dec 2, 2004 #5
    hehe:Dok then i will next time i'll post a thread with the title I have a phsycic powers is a math fourm:p that will surely attract some attention
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