Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
NCTM or The Math Forum.



Re: How Many Edges On SOLID CYLINDER
Posted:
Apr 1, 2002 5:47 PM


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 calculustype 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. > > IS THERE A DEFINIIVE ANSWER TO THE QUESTION: "HOW MANY EDES ARE THERE > ON A SOLI CYLINDER?" > > Thanks!



