## Elementary Geometry for College Students (6th Edition)

(a) $Line~ m$ and $Line~ t$ are parallel. (b) $Line~ m$ and $Line~ p$ are nonparallel.
(a) $Line~ m$ and $Line~ t$ point in the same direction, so they are parallel. (b) $Line~ m$ and $Line~ p$ point in different directions, so they are nonparallel.