1998 Fermat Problem 19

Square ABCD has sides of length 14. A circle is drawn through A and D so that it is tangent to BC, as shown. What is the radius of the circle?

\textbf{(A)}\ 8.5\quad \textbf{(B)}\ 8.75\quad \textbf{(C)}\ 9\quad \textbf{(D)}\ 9.25\quad \textbf{(E)}\ 9.5

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