Geometry - Circles

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Source: — Problem Solving |

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by Nycgrl » Sun Jun 22, 2008 6:08 pm
ans is E

radius of medallion is r
width of frame is S

Area of medallion without frame is Pi r^2--------------1
Area of medallion with frame is pi (r+s)^2 = pi(r^2 +s^2+2rs)--------2

Now Area of frame is 2-1
pi(r^2+s^2+2rs -r^2)
pi (s^2 +2rs)
pi s(s+2r)

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by rkotha » Tue Jun 24, 2008 9:58 am
That is what I solved it to be. But the answer choice E is not that

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by sibbineni » Tue Jun 24, 2008 3:55 pm
Area of medallion without frame is Pi r^2--------------1
Area of medallion with frame is pi (r-s)^2 = pi(r^2 +s^2-2rs)--------2

2-1

pi(r^2 +s^2-2rs)-Pi r^2==>pi s(2r-s)


so

IMO E

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by sibbineni » Tue Jun 24, 2008 3:55 pm
Area of medallion without frame is Pi r^2--------------1
Area of medallion with frame is pi (r-s)^2 = pi(r^2 +s^2-2rs)--------2

2-1

pi(r^2 +s^2-2rs)-Pi r^2==>pi s(2r-s)


so

IMO E

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by sibbineni » Tue Jun 24, 2008 3:57 pm
The calculayed radii is shown in figure
Image
[/img]