(2)A(-2 radical 3,0), B(2 radical 3,0),

Let b and d be AC vertical lines respectively. Let the intersection of AC and BD be e.

Triangle ACD= triangle ACB area = 1/2*AC* height.

So the height is equal. The certificate is congruent. Get BE=DE.

So AC divides BD equally.

Just asking. ...

(3) existence. AB=4 times the root number 3,

The distance from the highest point of parabola to A =4 times the root number 3, p (0,6),

You continue to testify ~