Greetings maibs89

Changing to polar coordinates we get (remember: )

setting z=0 gives

This tells us how far the radius goes out in the xy plane (z=0)

So the paramters are

To find the normal vector we need to take the gradient of F(x,y,z)=0

Note: there is not a normal vector at the tip of the cone x=y=0

I hope this helps.

Good luck.