## Calculus: Early Transcendentals (2nd Edition)

$\textbf{r} = \langle 0,0,1\rangle + t\langle1,0,0 \rangle$
Equation of a Line: $\textbf{r} = \textbf{r}_0 + t\textbf{v}$ $\textbf{r}_0 = \langle 0,0,1\rangle$ Since the line is parallel to the $x$-axis, the orientation of $\textbf{v}$ must be parallel to the $x$-axis. In other words, we can use the unit vector $\textbf{u}$ as our $\textbf{v}$. Thus, $\textbf{v} = \textbf{u}=\langle 1,0,0 \rangle$ $\textbf{r} = \langle 0,0,1\rangle + t\langle1,0,0 \rangle$