Determine if points $P, Q$ and $R$ are collinear, and if not, find a vector normal to the plane containing them.
I've never done a collinear problem. There are three sets of points for $P, Q,$ and $R$.
A) $P=(2,1,0), Q=(1,5,2)$ and $R=(-1,13,6)$
B) $P=(2,1,0), Q=(-3,21,10)$ and $R=(5,-2,9)$
C) $P=(1,1,0), Q=(1,-2,-1)$ and $R=(3,2-4)$
I have never had a problem like this and don't know where to start, or how to calculate a vector normal to the containing plane.
Find the slope of $PQ$ and $QR$. If they are equal, they are collinear. If they are not, find the cross product of $PQ$ and $QR$.