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find the volume of the solid whose base is bounded by the circle x^2+y^2=81 please help me !!?

find the volume of the solid whose base is bounded by the circle x^2+y^2=81 and square cross sections taken perpendicular to the x axis.

i can use the calculator on the test

so i do not need to integrate =) but i dont know how to do it

Update:

why would i not add pi to the front when solving for it?

3 Answers

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  • 7 years ago

    As a precalc student I would solve this by saying that the radius of the base is 9 cuz that's the root of 81. V=pi*r^2 *h. So we know r is 9 and since the cross sections are square, they must have a length (and in turn a height) equal to the diameter of the circular base. So the height is 18 and my answer to the question would be 1458pi. I'm probably totally wrong and have no idea what you're talking about but I thought I'd give it a shot haha

  • ted s
    Lv 7
    7 years ago

    volume = area x width....here the area is [ 2y ]² { a square } and width is [ dx ] , x in [ - 9 , 9 ]

    so V = int over x in [-9,9] of { 4 ( 81 - x² ) dx }...and why would you use a calculator on something

    as trivial as this ??

  • Eliot
    Lv 5
    7 years ago

    Your question doesn't make sense. What kind of solid?

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