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Feb 2, 2018
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Three concentric circles are drawn such that the area of the smallest circle is equal to the area of each of the rings.
If the radius of the largest circle is 12 cm,
what is the radius of the smallest circle?

 

Let smallest circle radius =rs Let middle circle radius =rm Let largest circle radius =rl 

 

πr2s=πr2mπr2s=πr2lπr2m|:πr2s=r2mr2s=r2lr2m

 

(1)2r2s=r2m(2)2r2m=r2l+r2s|r2m=2r2s2(2r2s)=r2l+r2s4r2s=r2l+r2s3r2s=r2l|3rs=rl|rl=123rs=12rs=123rs=12333rs=1233rs=43

 

The radius of the smallest circle is 43 cm 6.9 cm 

 

 

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Feb 2, 2018
 #1
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Feb 2, 2018

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