Hi,

 diameter doubled ⇒   and  

Answer by 55305(86)   (Show Source): You can put this solution on YOUR website!
 If the diameter is doubled, then the radius is also doubled. So we have the formula of finding the area of a circle:

A= (pi)*r^2,

where r is the radius and A is the area of the circle.

So if we multiply r times 2 and plug that into the formula instead of r, we get A= (pi)*(2*r)^2, and since (2*r)^2= 4*r^2 we can replace 4*r^2 with (2*r)^2.

So now the formula looks like this: 

A= (pi)*4*r^2, and if you compare that to the original formula of finding the area of a circle, you can see that an extra 4 is being multiplied, meaning that the area is 4 times as larger.



So if the diameter of the pizza is doubled, then total area quadruples(gets 4 times as larger). 

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