If they give you 3 points that are in a plane and ask you to find the equation of the plane, is there a systematic way to decide how to construct the vectors? For instance, if I have 3 points, a(0,1,1) b(1,0,1) c(1,1,0), I could use ca x cb to find the normal to the plane. I could also, just as easily, use ab x ac. The problem is, it makes it tough to check my answers with the book if I don't pick the same ones they do. Is there some standard way for doing this? Thanks.