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 ?