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### What is Circumference?

```
Date: 06/25/2001 at 12:48:12
From: raman
Subject: What is circumference?

What is circumference? My friend told me it's somewhat like the
measurement of the outside of a circle, but I don't understand that.
Can you help?
```

```
Date: 06/25/2001 at 13:31:58
From: Doctor Ian
Subject: Re: What is circumference?

Hi Raman,

Imagine a square, like

A       B
+-----+
|     |
|     |
+-----+
D       C

The 'perimeter' of the square is the sum of the distances

perimeter = AB + BC + CD + DA

That is, it is the length of the _path_ that you would have to take to
move all the way around the square, returning to the place where you
started.

We can extend the definition to regular polygons with more sides,
e.g.,

A _____ B
/     \
F /       \ C         perimeter = AB + BC + CD + DE + EF + FA
\       /
\_____/
E     D

(A 'regular' polygon is a polygon whose sides and angles are
identical. So a square is a regular polygon, but a parallelogram is
not.)

A circle is basically a regular polygon with an infinite number of
sides. For a circle, 'circumference' and 'perimeter' mean the same
thing.

The American Heritage Dictionary gives these definitions for
circumference:

http://www.bartleby.com/61/55/C0365500.html

1. The boundary line of a circle.
2a. The boundary line of a figure, area, or object.
2b. abbreviation c or circ. The length of such a boundary.

The word is originally from Latin circumferentia, from circumferns,
circumferent-, present participle of circumferre, meaning "to carry
around."

more, or if you have any other questions.

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
Elementary Circles
Elementary Definitions
Elementary Geometry
Elementary Triangles and Other Polygons
Middle School Conic Sections/Circles
Middle School Definitions
Middle School Geometry
Middle School Triangles and Other Polygons

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