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### Names of Parts of a Cone

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Date: 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
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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

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/
```
Associated Topics:
High School Definitions
High School Geometry
High School Higher-Dimensional Geometry
Middle School Definitions
Middle School Geometry
Middle School Higher-Dimensional Geometry

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