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If the radius of a circle is r cm, what is the area of the circle?  If the radius is increased to 2r cm, what is the area of the circle?

 Sep 15, 2014

Best Answer 

 #2
avatar+118117 
+8

Rose, you can get the formula for the area of a circle on the from the formulary page on this site.  It is

$$A=\pi r^2 \quad cm^2$$

 

Now if the radius is doubled it becomes 2r  the new area will be

$$\\A=\pi\times (2r)^2\\
A=\pi \times 2^2 \times r^2\\
A=4\pi r^2\quad cm^2\\$$

 Sep 15, 2014
 #1
avatar+11912 
+3

Rose do you know whats the formula to find the area of the circle , if so can u tell me?

 

 Sep 15, 2014
 #2
avatar+118117 
+8
Best Answer

Rose, you can get the formula for the area of a circle on the from the formulary page on this site.  It is

$$A=\pi r^2 \quad cm^2$$

 

Now if the radius is doubled it becomes 2r  the new area will be

$$\\A=\pi\times (2r)^2\\
A=\pi \times 2^2 \times r^2\\
A=4\pi r^2\quad cm^2\\$$

Melody Sep 15, 2014

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