In the figure above, $$\overline {AB}$$, which has length z cm, is tangent to the circle at point A, and $$\overline {BD}$$, which has length y cm, intersects the circle at point C. If $$BC= x$$ cm and $$z = \sqrt{xy}$$ , what is the value of x ?
(1) CD=x cm
(2) z =$$5\sqrt{2}$$