Equation x solution: (1)? -4X+3=0 can solve the equation, and the coordinates of point A and point B are (-1, 0) and (3,0) respectively, so AB=4. Because ∠ DAB = 45 and △DAB are right isosceles triangles, the height of this triangle is the distance from point D to the X axis, and the coordinate of point D is (. -X- 1.5

(2) Because AC⊥AD, the intersection point C is perpendicular to the X-axis, and the X-axis intersects with the E-point, because ∠ DAB = 45, so ∠ Cab = 45, so △CAE is a right-angled isosceles triangle, so CE=AE, let the coordinates of point C be (a, b), then b =. -X- 1.5 gives two points (-1, 0) and (5,6). Because (-1, 0) is the coordinate of A, the coordinate of point C is (5,6).

(3) As can be seen from the figure, the maximum value of d 1+d2 should be obtained when AP⊥CD (the length of any right side of a right triangle is less than the length of the hypotenuse). According to the coordinates of C and D, CD=4√5, so the maximum value of d 1+d2 is 4√5.