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Picture is not drawn to scale.


The dimensions of circle B are twice the dimensions of circle A. The area of circle Bis 64 cm2.

What is the area of circle A?

Guest Feb 25, 2015

Best Answer 

 #2
avatar+93335 
+5

the radii are in the ratio 1:2

so the area has to be in the ratio     $$1^2:2^2\quad=\quad 1:4$$

the big one's area is 64pi 

so the little ones area is          $$64\pi/4 = 16\pi \quad cm^2$$

Melody  Feb 26, 2015
 #1
avatar+88899 
+5

If the area of circle B = 64*pi cm^2, it's radius must be 8 cm.

Then, the radius of circle A must be 1/2 of that = 4cm

And it's area = pi*(4cm)^2  = 16pi cm^2

 

CPhill  Feb 26, 2015
 #2
avatar+93335 
+5
Best Answer

the radii are in the ratio 1:2

so the area has to be in the ratio     $$1^2:2^2\quad=\quad 1:4$$

the big one's area is 64pi 

so the little ones area is          $$64\pi/4 = 16\pi \quad cm^2$$

Melody  Feb 26, 2015

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