As we all know, as shown in the figure, the triangle ABC is an isosceles right triangle, ∠ ACB = 90, F is the midpoint of AB, and the straight line L passes through point C, and points A and B respectively pass through as the vertical lines of L, namely, AD⊥CE, BE⊥CE,

(1) As shown in figure 1, when CE is located on the right side of point F, verify: △ ADC △ CEB;

(2) As shown in Figure 2, when CE is located to the left of point F, verify that ED = be-ad;

(3) As shown in Figure 3, when CE is outside △ABC, try to guess the quantitative relationship among ED, AD and BE, and prove your guess.