Given 3 points, how do I calculate the normal vector?

Question

Given three 3D points (A,B, & C) how do I calculate the normal vector? The three points define a plane and I want the vector perpendicular to this plane.

Can I get

Answer 1

You need to calculate the cross product of any two non-parallel vectors on the surface. Since you have three points, you can figure this out by taking the cross product of, say, vectors AB and AC.

When you do this, you're calculating a surface normal, of which Wikipedia has a pretty extensive explanation.