OA=OA'=3

∴A'(3,0)

Let the analytical formula of parabola be y=ax2+bx+c, then

a-b+c=0 a=- 1

C=3，b=2。

9a+3b+c=0 c=3

The analytical formula of this parabola is y=-x2 +2x+3.

(2) If you are tired of typing, don't type. Just to remind you, triangles are similar.