It is known that in △ABC, AB=4, BC=6, AC > AB, D is a point on the side of AC, DC=AB, E is the midpoint of the side of BC, connect de, and let AD = X. ..

(1) when DE⊥BC (as shown in figure 1), find the value of x;

(2) setting? , find the functional relationship between y and x, and write the domain;

(3) Take the midpoint m of AD, connect EM, and extend the extension line of intersection BA to point P, with A as the center and AM as the radius, and make ⊙ A.. Question: When the length of AD changes, does the positional relationship between point P and point ⊙A change? If there is no change, please explain the specific positional relationship and prove your conclusion; If yes, please explain why. (20 1 1? Yangpu)