When does a line and a plane appear to be parallel?

Question

Is it when the line is on the plane? Or is it when the line is not on the plane?

Answer 1

when their slope is equal

Answer 2

when it is not on the plane but the a line drawn perpendicular from the line is also perpendicular to the plane

AM

Answer 3

1) When the line's directing vector is orthogonal to the plane's one (referred to as the normal vector).

2) If you want the line to lie on the plane, then you need to require 1) + the existence of a point belonging to both the line and plane.

Answer 4

It may be both. As long as their slopes are equal. But must likely, on the plane because you are sure their slopes are equal!