I want to describe the tetrahedron that use those 4 points $$A(1,2,3) , B(-1,2,0) , C(1,0,1) , D(0,1,1)$$
So I figured by drawing it down that I have to make vectors between each points
$$\vec V1=\vec {OA} - \vec {OB} , \vec V2=\vec {OA} - \vec {OC}, \vec V3=\vec {OB} - \vec {OC}$$
$$\vec V4=\vec {OB} - \vec {OD} , \vec V5=\vec {OC} - \vec {OD}$$
$$\vec V6=\vec {OA} - \vec {OC} - \vec {OD}$$ $$\vec V7=\vec {OB} - \vec {OA} - \vec {OD}$$ $$\vec V8=\vec {OA} - \vec {OC} - \vec {OB}$$
not quit sure about the last ones.
Then we have $$\vec V1 = [0, 0, -3]$$ $$\vec V2 = [0, -2, -2]$$
I am wondering if
- I'm doing the right thing
- Why do we have to use - between points instead of + to form a vector ?