Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 7 - Applications of Trigonometry and Vectors - Section 7.4 Vectors, Operations, and the Dot Product - 7.4 Exercises - Page 331: 76

Answer

$-4$

Work Step by Step

Step 1: $2\textbf{i}+4\textbf{j}$ can be written as $\langle 2,4 \rangle$. On the other hand, $-\textbf{j}$ is basically $0\textbf{i}-1\textbf{j}$ which means it can be written as $\langle 0,-1 \rangle$. Step 2: $\langle 2,4 \rangle \cdot \langle 0,-1 \rangle$ Step 3: $2(0)+4(-1)$ Step 4: $0-4$ Step 5: $-4$
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