(2) Taking AC as the diagonal, the midpoint of AC (5/2, 1/2) is obtained by the midpoint formula.

(x+2)/2=5/2 x=3

﹛ =>﹛

(y-2)/2= 1/2 y=3

(3) B as BF∨X axis, Y axis in F, and then EF∨AB as X axis in E.

∴ e (2，0)，F(0，2)。 Or e (-2,0), f (0 0,2)