$\vec{b}$

$\vec{a}$

$\vec{c} = \vec{b} - \vec{a} $

\vec{a} = \left(\begin{array}{c} a_1\a_2\ a_3\end{array}\right) 

\vec{b} = \left(\begin{array}{c} b_1\b_2\ b_3\end{array}\right) 

\vec{c} = \vec{b} - \vec{a} = \left(\begin{array}{c} b_1-a_1\b_2-a_2\ b_3-a_3\end{array}\right) 

Q: (4, 3, 2)
R: (-6, 0, 3)
P: (5, -1, 1)
S: (-5, -4, 3)
pq = Vector(P, Q)
ps = Vector(P, S)
a: (pq * ps)
rs = Vector(R, S)
rq = Vector(R, Q)
b: (rs * rq)
c: (rs * ps)
sq = Vector(S, Q)