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by moliver » Sun Apr 25, 2010 6:03 pm
is E the OA?

The radius of medallion - the area of the center part = area of the border

pi r^2- pi(r-s)^2
pi (r^2 - r^2 + 2rs - s^2 )

= pi (2rs - s^2 )

please let me know if it help you

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by Testluv » Sun Apr 25, 2010 10:23 pm
moliver's answer is correct.

Just wanted to point out that whenever we have a shaded region, we have:

area of whole figure = area of shaded region + area of non-shaded region

they'll almost always ask you to compute the area of the shaded region, so:

area of shaded region = area of whole figure - area of non-shaded region

In this question, the radius of the whole figure (the medallion) is "r" while the radius of the non-shaded region is "r - s"
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by moliver » Mon Apr 26, 2010 2:54 am
Interesting point Testluv
Thank for sharing it