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Radius of a Pizza


Date: 8/27/96 at 3:56:15
From: Chuck Francis
Subject: Radius of a Pizza with Area...

If a pizza has an area of 30 inches square, what is its radius? What 
are the steps in solving this problem?


Date: 8/27/96 at 4:33:48
From: Doctor Mike
Subject: Re: Radius of a Pizza with Area...

Hello,

This is just what I need; a late-night pizza question!
  
Just about the most famous math formula is known as "pie are 
square", or seriously, 

"The area of a circle is pi times the square of the radius length, or 
A = pi*r^2."

You know that the area is 30 square inches, so 30 = pi*r^2.  This is 
an equation in the unknown length r.  

Divide both sides of the equation by pi to get r^2 is 30/pi 
which is about 30/3.1415926535898 which is in turn about 9.5492966.  
Then r is the square root of this, which comes out to approximately 
3.09 inches. 
  
Hey!  This must be a Personal Pan Pizza (c) which is not big 
enough to share with me.  I'm going off to get a snack. G'nite.
  
I hope this helps.  

-Doctor Mike,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/   
    
Associated Topics:
Middle School Conic Sections/Circles
Middle School Geometry
Middle School Pi
Middle School Word Problems

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