1994 AHSME Problem 4

In the xy-plane, the segment with endpoints (-5,0) and (25,0) is the diameter of a circle. If the point (x,15) is on the circle, then x=

\textbf{(A)}\ 10 \qquad\textbf{(B)}\ 12.5 \qquad\textbf{(C)}\ 15\qquad\textbf{(D)}\ 17.5 \qquad\textbf{(E)}\ 20

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.