Chapter 11 - Vectors and Vector-Valued Functions - 11.1 Vectors in the Plane - 11.1 Exercises - Page 767: 14

$\dfrac{\overrightarrow{v}}{|v|},-\dfrac{\overrightarrow{v}}{|v|}$

We consider the unit vector $\dfrac{\overrightarrow{v}}{|v|}$, which is parallel to $\overrightarrow{v}$. Another unit vector also parallel to $\overrightarrow{v}$ is $-\dfrac{\overrightarrow{v}}{|v|}$.