SOLUTION: “Three concentric circles have radii of a, 2a, and 3a. Find the area of the outer ring and the middle ring.” I think the outer area is A=pi(3a)^2 and the middle area is A=pi(2a)^2,

Algebra ->  Circles -> SOLUTION: “Three concentric circles have radii of a, 2a, and 3a. Find the area of the outer ring and the middle ring.” I think the outer area is A=pi(3a)^2 and the middle area is A=pi(2a)^2,      Log On


   

Question 1107007: “Three concentric circles have radii of a, 2a, and 3a. Find the area of the outer ring and the middle ring.” I think the outer area is A=pi(3a)^2 and the middle area is A=pi(2a)^2, but I’m not very sure.
Answer by ikleyn(52898) About Me  (Show Source):
You can put this solution on YOUR website!
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The area of the outer ring is the difference 

    A = pi%2A%283a%29%5E2 - pi%2A%282a%29%5E2 = pi%2A%289a%5E2+-+4a%5E2%29 = 5pi%2Aa%5E2.



The area of the middle ring is the difference 

    A = pi%2A%282a%29%5E2 - pi%2Aa%5E2 = pi%2A%284a%5E2+-+a%5E2%29 = 3pi%2Aa%5E2.