1 pair of parallel line
perpendicular line
1 pair of parallel lines
The answer is that the parallel lines extend infinitely in both directions, and the line segment has two endpoints.
Parallel lines
A pair of parallel lines are equidistance apart and never intersect each other.
A cross is a pair of intersecting lines.
A transversal line intersects parallel lines creating various angles.
Any polygon, other than a triangle, can have a pair (or more) of parallel lines.
2 pairs of two lines.
A pair of parallel lines, an ellipse or a circle.
Pair of radii