AHSME 1969 Problem 6

The area of the ring between two concentric circles is $12\tfrac{1}{2}\pi$ square inches. The length of a chord of the larger circle tangent to the smaller circle, in inches, is: $\text{(A) } \frac{5}{\sqrt{2}} \text{(B) } 5 \text{(C) } 5\sqrt{2} \text{(D) } 10 \text{(E) } 10\sqrt{2}$