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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

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