Associated Topics || Dr. Math Home || Search Dr. Math

### Circle Area and Circumference

```
Date: 03/16/2002 at 19:21:22
From: Briddy
Subject: Area and Circumference

I need help with area and circumference. Are radius and diameter the
same thing as area and circumference?
```

```
Date: 03/17/2002 at 11:18:14
From: Doctor Sarah
Subject: Re: Area and Circumference

Hi Briddy - thanks for writing to Dr. Math.

The circumference of a circle is the distance around it. It is
measured in linear units (inches, feet, etc.). The formula for the
circumference of a circle is:

C = pi*d (pi times the diameter)

The diameter of a circle is a chord that passes through the center of
the circle. (A chord is a line segment with endpoints on the
circumference of a circle.)

The area of the circle is the number of square units needed to cover
its surface. It is measured in square inches, square feet, etc. The
formula for the area of a circle is:

A = pi * r^2 (pi times the radius squared)

The radius of a circle is a line segment with one endpoint at the
center of the circle and the other endpoint on the circumference of
the circle. It is exactly half the diameter of the circle.

Does this help?

- Doctor Sarah, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
Elementary Circles
Elementary Geometry
Elementary Two-Dimensional Geometry

Search the Dr. Math Library:

 Find items containing (put spaces between keywords):   Click only once for faster results: [ Choose "whole words" when searching for a word like age.] all keywords, in any order at least one, that exact phrase parts of words whole words

Submit your own question to Dr. Math
Math Forum Home || Math Library || Quick Reference || Math Forum Search