Consider the picture to the right. We have two concentric circles, one inside another. We do not know the radius for either one of them.

We do, however know that the chord (shown in red) - a line whose ends are on the outer circle and which is tangent to the inner circle - has a length of 10 inches.

What is the area (shaded in light-blue) between the two circles?

I read Levik's Solution. It most certainly is not the best. The best solution appeared in several similar forms in comments by Tom, Narcoleptic, TomM and Fizzle and seems to have been ignored, viz. by allowing the inner circle to approach zero, the chord appraoches the diameter of a 10 inch circle with an area of 25pi.

Posted by CeeAnne on 2004-10-04 21:24:40