We are asked to examine the following statement to determine if it is always, sometimes, or never true.
If linemlies in planeX
and linemcontains a pointQ,
then pointQlies in planeX.
We say that a line lies in a plane if all points of the line are in the plane. It is given that line m lies in plane X, so all points of line m are in plane X.
It is also given that Q is a point on line m. Since all points of line m are in plane X, we can conclude that Q is in plane X.
Thus, it is always true that if Q is a point on a line m which is contained in plane X, then point Q is in plane X.
