SOLUTION: How do you find the surface area of a border around a circle. Do you use the same formula as the surface are for a circle? 3.14 x Radius squared? An example would be ... you have a

Algebra ->  Surface-area -> SOLUTION: How do you find the surface area of a border around a circle. Do you use the same formula as the surface are for a circle? 3.14 x Radius squared? An example would be ... you have a      Log On


   

Question 596553: How do you find the surface area of a border around a circle. Do you use the same formula as the surface are for a circle? 3.14 x Radius squared? An example would be ... you have a circle with a border that goes all around the circle and is 1ft away from it...
Thanks, Victor
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
How do you find the surface area of a border around a circle. Do you use the same formula as the surface are for a circle? 3.14 x Radius squared? An example would be ... you have a circle with a border that goes all around the circle and is 1ft away from it...
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The area (I don't know why you call it surface area) is the area of the outside circle minus the area of the inside circle.
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If the difference is 1 inch radius, it's
pi%2A%28r%2B1%29%5E2+-+pi%2Ar%5E2+=+pi%2A%282r%2B1%29 where r is the radius of the inside circle.