parabola question

[drufae]

I've tried to find the answer but can't seem to get it yet.

Here is the question:

For what values of 'a' will the tangents to the parabola

[math] y^2 = 4ax[/math]from a point not on the y axis will be normal to the parabola [math] x^2 = 4y [/math]?

in case this help the answer is [math] a < -2 \sqrt[2]{2} or a > -2 \sqrt[2]{2} [/math].

 

sorry for this repost. Does anyone know if I could delete it.

 

thanks for deleting the other one