Math Forum - Ask Dr. Math

The Math Forum

$Ask Dr. Math - Questions and Answers from our Archives$ $_____________________________________________$
Associated Topics || Dr. Math Home || Search Dr. Math
$_____________________________________________$

Area of an Annulus


Date: 10/13/2001 at 23:15:14
From: Cindy
Subject: Geometry

I wanted to know how you would find the area of an annulus.

Date: 10/14/2001 at 12:54:18
From: Doctor Sarah
Subject: Re: Geometry

Hi Cindy - thanks for writing to Dr. Math.

A ring, or annulus, with outer radius x and inner radius y, has area

   pi(x^2 - y^2)

And see #15 at 

   Circumference and Area of Circles, Part I - ICSE. Maths
   http://www.icsemaths.com/Part1-circumfe.htm   

(the answers are at the bottom of the page).

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/

Associated Topics:
High School Conic Sections/Circles
High School 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

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search
_____________________________________