Given a (- 2,0), B (2,0), point C and point d satisfy | AC | = 2, vector ad = 1 / 2 (vector AB + vector AC) (1) Finding the trajectory equation of point d (2) Through point a, make a straight line L to intersect the ellipse with a and B as the focus at two points m and N, the distance from the midpoint of line Mn to y axis is 4 / 5, and the line L is tangent to the trajectory of point D, so the equation of the ellipse can be obtained Especially the second question is so difficult

Given a (- 2,0), B (2,0), point C and point d satisfy | AC | = 2, vector ad = 1 / 2 (vector AB + vector AC) (1) Finding the trajectory equation of point d (2) Through point a, make a straight line L to intersect the ellipse with a and B as the focus at two points m and N, the distance from the midpoint of line Mn to y axis is 4 / 5, and the line L is tangent to the trajectory of point D, so the equation of the ellipse can be obtained Especially the second question is so difficult

Let C (XC, YC), D (x, y), then the trajectory equation of vector AB = (4,0), vector AC = (XC + 2, YC), vector ad = (x + 2, y) ∵|| AC | = 2  C is: (XC + 2) & sup2; + YC & sup2; = 4 (1) ∵ vector ad = 1 / 2 (vector AB + vector AC) ≠ algebraically expressed as: x + 2 = 1 / 2 (XC + 2 + 4) y = 1 / 2yc