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Topic: How Many Edges On SOLID CYLINDER
Replies: 3   Last Post: Oct 26, 2004 9:16 AM

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Guy Brandenburg

Posts: 714
Registered: 12/3/04
Re: How Many Edges On SOLID CYLINDER
Posted: Apr 1, 2002 5:47 PM
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I suppose it depends on what you define as an edge. I believe that most
math types would think of it as a straight line segment that is the
boundary of two polygonal faces; it runs between two vertices, which are
points where 3 polygonal faces meet. Now, since a cylinder has no
polygonal faces, then it has no edges at all.

That being said, many people not familiar with mathematical terminology
might indeed consider the boundaries of the two circles as being edges.
But that would not correspond to the normal mathematical definitions of
polyhedra, prisms, pyramids, and so on. A cone is not the same thing as
a pyramid, for example; a cylinder is not a prism.

On the other hand, one could think of the circular bases as being
polygons with an infinite number of sides. In that case, there would be
an infinite number of edges. But that would make the lateral, curved,
sides into no longer curved sides but an infinite number of infinitely
thin rectangles. Probably better not take that approach unless you are
trying to do calculus-type computations.

I am guessing that the expected answer was zero.

Guy Brandenburg

David Saray wrote:
> I was amazed t the previous email chain.
> I too am trying to assist my grader research an incorrect test answer
> that he thinks was correct.
> How many edges are there on a solid cylinder?
> He put "2" he got it wrong and asked his dear old dad to research
> onthe net and find if it was really wrong.
> Thanks!

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