Finding a Circle's Area Without Pi

Date: 02/24/2001 at 22:02:14
From: Anna
Subject: Finding the area of a circle without using pi

I need to find out how to find the area of a circle without using pi. 
I have to explain it and prove the answer.

Please help.

Date: 02/25/2001 at 13:17:55
From: Doctor Roy
Subject: Re: Finding the area of a circle without using pi

Hello,

Thanks for writing to Dr. Math.

There is a way, although it's really more of a cheat. Remember how pi 
is defined. It is the ratio of the circumference of a circle to its 
radius, or:

     pi = C/d

Now the area of a circle is given by the following formula:

     A = pi*r^2

We can combine these two facts to get an expression that does not have 
pi in it. Of course pi will be involved, but it will be hidden in the 
interaction between circumference and diameter.

I hope this helps.

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