## Calculus (3rd Edition)

The length of $e\times f$ is $\frac{1}{2}$.
We have $$\|e\times f\|=\|e\|\|f\| \sin \frac{\pi}{6}=(1)(1)(\frac{1}{2})=\frac{1}{2}.$$ Hence, the length of $e\times f$ is $\frac{1}{2}$.