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undvaulter
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circle square area ratio

by undvaulter Tue Apr 13, 2010 7:46 am

If circle A has 3 times the area of circle B, and circle B has one-sixth of the area of square WXYZ, what is the ratio of the area of a circle inscribed within WXYZ to that of the area of circle A?

Π/12

Π/6

Π/2

2/Π

sqrt12Π
ps63739
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Re: circle square area ratio

by ps63739 Tue Apr 13, 2010 10:16 am

Let area of circle A = pie*x^2
Area of circle B = 3pie*x^2
Area of square = 18pie*x^2, side of square = 3x*sqrt(2*pie) (Which is diamater for the circle inscribed in square)
Area of the circle in square = pie*(9/4)*2*pie*x^2

Ratio = (3piex^2)/((pie^2*9/2)x^2)
thoppae.saravanan
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Re: circle square area ratio

by thoppae.saravanan Tue Apr 13, 2010 7:02 pm

ACA = Area of Circle A
ACB = Area of Circle B
AS = Area of square WXYZ
ACS = Area of circle inscribed in square WXYZ

Given, ACA = 3 ACB and ACB=AS/6.

Let the radius of ACS = r.

Then, AS = 4r^2 => ACB = 2r^2/3 => ACA = 2r^2.

So ACS/ACA = pi*r^2/2r^2 = pi/2. Option C should be the answer.

OA please.
undvaulter
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Re: circle square area ratio

by undvaulter Fri Apr 16, 2010 12:29 am

OA is Pi/2

thanks thoppae
Ben Ku
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Re: circle square area ratio

by Ben Ku Wed Apr 28, 2010 11:47 pm

Please cite the source (author) of this problem. We cannot reply unless a source is cited (and, if no source is cited, we will have to delete the post!). Thanks.
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