You can use any two points on a line to name it. Coplanar points lie in the same plane.
Example Solution:
Other names for ST: SP and PT
Point not coplanar with Q, S, and T: V
Practice makes perfect
Let's look at each of the two given tasks one at a time.
The line ST
We can use any two points on a line to name it. First, we will note that there are three points on ST: S, T, and P.
Any two of these three points can be used to name ST. We can arbitrarily choose the names SP and PT for the line. Note that m would also be a correct name for ST.
The point
For us to name a point that is not coplanar with Q, S, and T, we first have to figure out what plane QST looks like. These points are not collinear — there is only one plane on which they all lie. This plane intersects plane R along ST and is drawn in the diagram as follows.
We can now see that V is the only point that does not lie on plane QST — it is not coplanar with Q, S, and T.
