## Calculus (3rd Edition)

Published by W. H. Freeman

# Chapter 13 - Vector Geometry - 13.3 Dot Product and the Angle Between Two Vectors - Exercises - Page 666: 19

#### Answer

$$\theta=\frac{\pi}{2}.$$

#### Work Step by Step

\begin{align*} \cos \theta &=\frac{\langle 0,3,1\rangle \cdot \langle 4,0,0\rangle}{\|\langle 0,3,1\rangle\|\|\langle 4,0,0\rangle\|}\\ &=\frac{0}{\sqrt{10}\sqrt{16}}\\ &=0. \end{align*} That is $$\theta=\frac{\pi}{2}.$$

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