"Alasdair" wrote in message
news:s20g241s5ec7c900aeeqaj9ik3lndndibh@4ax.com...
> On Mon, 12 May 2008 00:28:47 -0700 (PDT), George
> wrote:
>
>>"I am a 3d shape. I have one flat face. I have one curved face which
>>meets at a vertex. What am I?"
>>
>>My 8 year old son's homework. Oh dear - I can't see how a flat face
>>can meet a curved face at a vertex. All the rest are quite easy, or is
>>it just me?
>>
>>Help, George.
>
> A cone?
http://mathforum.org/library/drmath/view/54681.html
"Dear Dr Math
Our 4th grade math textbook defines a cone as "A solid figure with
one circular face and one vertex." This sounds reasonable until you
read the textbook's definitions for face, edge, and vertex. The
textbook defines a face as "A flat surface of a solid." It defines an
edge as "A line segment where two faces of a solid meet." It defines a
vertex as "A point where two or more edges meet."
Assuming that these definitions are accurate and that I'm not
misinterpreting them, a cone must not have a vertex. If a cone has
only one face, then it can't possibly have an edge. Therefore, if it
doesn't have an edge, it can't have a vertex. "
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