Calculus (3rd Edition)

Published by W. H. Freeman
ISBN 10: 1464125260
ISBN 13: 978-1-46412-526-3

Chapter 13 - Vector Geometry - Chapter Review Exercises - Page 702: 22



Work Step by Step

$$\cos\theta=\frac{v\cdot w}{\|v\|\|w\|}=\frac{-9}{\sqrt{1+9+4}\sqrt{4+1+16}}=\frac{-9}{\sqrt{14}\sqrt{21}}.$$ Hence $$\theta=\cos^{-1}\frac{-9}{\sqrt{14}\sqrt{21}}=2.123~ rad.$$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.