Given the right triangle paper sheet ABC , AC = 15cm, ∠B = 90°

(1) If AB=8.5cm , fold the triangle ABC to make point B fall on the side of AC as point E , the line made by folding is AD 。Find the length of EC .

(2) Assuming AB = x , first fold the triangle as (1) ,and then fold the triangle ADE along the line DE to make point A fall on the ray of EC as point F . In the folded shape, if the segment CF= \dfrac{1}{2}EF , what is the value of x ?