Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 7 - Applications of Trigonometry and Vectors - Section 7.5 Applications of Vectors - 7.5 Exercises - Page 342: 10

Answer

Magnitude: $25$ Direction angle: $106.26^{\circ}$

Work Step by Step

The magnitude $|u|$ of vector $u=\left\langle a,b\right\rangle$ is given by $|u|=\sqrt {a^2+b^2}$. For the given vector $u=\left\langle -7,24\right\rangle \Rightarrow ~ a=-7, b=24.$ Therefore, $|u|=|\left\langle -7,24\right\rangle|=\sqrt {(-7)^2+(24)^2}=\sqrt {49+576}=\sqrt {625}=25$ Hence the magnitude of the vector $\left\langle -7,24\right\rangle$ is $25$. The direction angle $\theta$ of vector $u=\left\langle a,b\right\rangle$ is given by $\theta=\tan^{-1}\left(\frac{b}{a}\right)$ Therefore, for $u=\left\langle -7,24\right\rangle $ we have $\theta=\tan^{-1}\left(\frac{24}{-7}\right)=106.26^{\circ}$ Hence, the magnitude of $\left\langle -7,24\right\rangle$ is $25$ and the direction angle is $106.26^{\circ}$
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