(2) It is proved that CD⊥AC is the correct conclusion, and the intersection point A is the point F perpendicular to the Y axis, then AFC ∠AFC is 90 degrees in the right triangle, which is equal to the right angle ∠ COD, ∠ACF=∠CDO of the right triangle C0D, and because x⊥AB, ab∨fo.

(3) let's assume that d moves to b, d.