SOLUTION: Two concentric circles are drawn so that the shaded area is equal to the unshaded area. The radius of the outer circle is 12cm. Find the difference in the radii of the two circles

Algebra ->  Circles -> SOLUTION: Two concentric circles are drawn so that the shaded area is equal to the unshaded area. The radius of the outer circle is 12cm. Find the difference in the radii of the two circles       Log On


   

Question 1148865: Two concentric circles are drawn so that the shaded area is equal to the unshaded area. The radius of the outer circle is 12cm. Find the difference in the radii of the two circles
Example of diagram: https://imgur.com/a/KQuBAVB
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
Given, the outer area equals the inner area, pi%2A12%5E2-pi%2Ar%5E2=pi%2Ar%5E2

144pi=2pi%2Ar%5E2
72pi=pir%5E2
r=6%2Asqrt%282%29

Difference between radii,
12-6sqrt%282%29