How to show that two surfaces are perpendicular at a point?

[mammothrob]

I have an equation for a sphere and an equation for another surface. I need to prove they are perpendicular at a particular point.

Do I do this by find the gradiant for each, evaluating the gradiant at that point? Any ideas?

 

[marcmtlca]

if they are perpendicular does it mean their normal vectors are perpendicular?

 

[pka]

Re: How to show that two surfaces are perpendicular at a poi

I have an equation for a sphere and an equation for another surface. I need to prove they are perpendicular at a particular point. Do I do this by find the gradiant for each, evaluating the gradiant at that point?

The gradiant is normal to the surface.
So see if their gradiants are perpendicular.