When given 3 points(vertices), which one should you pick to do the your calculations with.
E.g.: $P1=(1,-1,1) P2=(2,1,-1) P3=(1,-2,-1) $
I can pick P1 -> P2 and P1 -> P3. Then do my cross multiplication and so on to find the area.
What I don't understand is how to pick the right point ? Because picking a different one will give you a different answer for the cross multiplication. E.g.: P2->P1 and P2->P3 or even P1->P3 & P1->P2