Names of Parts of a ConeDate: 8/2/96 at 19:31:33 From: Bonnie Seiler Subject: Names of Parts of a Cone Hi Dr. Math! I'm interested in the components of the net of a cone. Are the components of a net called faces in all cases, or only for polyhedra? Could you please tell me what the wedge-like "face" is called? It's actually a sector of a circle, I guess. Also, can you refer to "faces" of a cone and cylinder, or are they not faces, since they are curved instead of flat? Can you recommend any sources for information on nets of basic 3D figures (say grade school through grade 6)? Date: 10/24/96 at 10:33:16 From: Doctor Tim Subject: Re: Names of Parts of a Cone As to the name for that curved surface (is it a face?) I have to admit I don't know and the people I asked didn't know either, and neither did the book we consulted. The dictionary at my side, however, (a Webster) defines face partly as a "principal or bounding surface" so in that sense it may well apply. But I have to admit it "feels" wrong, and, as a writer, I might avoid it since it might make the reader stumble and be confused (unless you set it up really well and use it consistently). As for me, I always call it "the curved surface of a cone," which also works for cylinders. And you can always use graphics! You're right, by the way, that the curved surface is a sector of a circle (unlike a sphere, it lies flat). Interestingly enough, when that sector is a semicircle, the cross-section of the resulting cone that goes through its vertex is an equilateral triangle. More of the circle, it's flatter; less, it's more pointy. -Doctor Tim, The Math Forum Check out our web site! http://mathforum.org/dr.math/ Date: 10/24/96 at 10:47:44 From: Doctor Ken Subject: Re: Names of Parts of a Cone Hi Bonnie - There's a computer program for constructing nets of 3D figures, called HyperGami. For more information, see http://mathforum.org/~sarah/HTMLthreads/articletocs/hypergami.paper.sculpture.html There's also a Math Forum web page about polyhedra and how to build them. You can find it at: http://mathforum.org/sum95/math_and/poly/polyhedra.html A good place to start looking for things like this is the Math Forum searcher, at http://mathforum.org/grepform.html Happy netting! -Doctor Ken, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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