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Math Help - circular cross sections

  1. #1
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    circular cross sections

    Hello.

    The question is which shapes have circular cross sections? My child has said cone, sphere and a cylinder.


    Next question is "can you make a gneral rule abou the kind of shapes that have circular cross sections?

    My child said he thought that a shape with a circle would have a circular cross section.

    Does the above sound correct as an answer. Thank you for reading.
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  2. #2
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    Hello, fecoupefe!

    The question is: which shapes have circular cross-sections?
    My child has said: cone, sphere and a cylinder.
    The question is too vague . . .

    A sphere has a circular cross-section no matter at what angle the plane cuts the sphere.

    A cone has a circular cross-section if the plane is perpendicular to its axis.
    The same is true for a cylinder . . . or an hourglass . . . or a cable.

    Take a king-size bedsheet and push it halfway through a napkin ring.
    We have a "shape" that has one circular cross-section.
    Does that count?

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  3. #3
    Senior Member mollymcf2009's Avatar
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    Quote Originally Posted by fecoupefe View Post
    Hello.

    The question is which shapes have circular cross sections? My child has said cone, sphere and a cylinder.


    Next question is "can you make a gneral rule abou the kind of shapes that have circular cross sections?

    My child said he thought that a shape with a circle would have a circular cross section.

    Does the above sound correct as an answer. Thank you for reading.
    Those are all correct. As far as a "general rule" I guess you could say that, if the cross section of a shape is circular, it will have a radius and be continuous. I guess that should cover the criteria. Hope tht helps
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  4. #4
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    Soroban...

    a delight to one's eyes to see you answer my question! Yes, agree the question is too vague, but the class is at the beginning of this "stuff". And thanks for throwing in the king size bedsheet with napkin ring just to make the brain even hurt more... !
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