Parallel lines close parallel lines Lines which never meet and stay the same distance apart. Parallel lines are indicated by a pair of arrows. are two or more straight lines that remain the same ...

Let v be the angle between two straight lines in space, and let $\mathrm{\varphi }\left(\overrightarrow{\mathrm{n}}\right)$ be the angle between the orthogonal projections of the same lines into a ...