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Three concentric circles are shown. The two largest circles have radii of 12 and 13 If the area of the ring between the two largest circles equals the area of the smallest circle, determine the radius of the smallest circle.

 Jun 9, 2019
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The area between the largest two circles  =  pi  (13^2 - 12^2)  =  pi (169 - 144)  = 25 pi

 

So....the radius of the smaller circle  must  be

 

25 pi = pi (radius)^2

 

25  = radius^2

 

5 = radius

 

 

cool cool cool

 Jun 9, 2019

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