Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 4 - Review Exercises - Page 645: 45

Answer

The six trigonometric functions are: $\sin \theta =-\frac{5\sqrt{26}}{26}\text{; cos}\theta \text{=}-\frac{\sqrt{26}}{26}\text{; tan}\theta \text{=5; csc}\theta \text{=}-\frac{\sqrt{26}}{5};\text{ sec}\theta \text{=}-\sqrt{26};\text{ cot}\theta \text{=}\frac{1}{5}$.

Work Step by Step

Here, $ x=-1\text{ and }y=-5$. Then, $\begin{align} & r=\sqrt{{{\left( -1 \right)}^{2}}+{{\left( -5 \right)}^{2}}} \\ & =\sqrt{1+25} \\ & =\sqrt{26} \end{align}$ Now, evaluate the sine functions as follows: $\begin{align} & \sin \theta =\frac{y}{r} \\ & =\frac{-5}{\sqrt{26}} \\ & =\frac{-5\sqrt{26}}{\sqrt{26}\cdot \sqrt{26}} \\ & =-\frac{5\sqrt{26}}{26} \end{align}$ Then, evaluate the cosine functions as follows: $\begin{align} & \cos \theta =\frac{x}{r} \\ & =\frac{-1}{\sqrt{26}} \\ & =\frac{-1\sqrt{26}}{\sqrt{26}\cdot \sqrt{26}} \\ & =-\frac{\sqrt{26}}{26} \end{align}$ Then, evaluate the tangent functions as follows: $\begin{align} & \tan \theta =\frac{y}{x} \\ & =\frac{-5}{-1} \\ & =5 \end{align}$ Then, evaluate the cosecant functions as follows: $\begin{align} & \csc \theta =\frac{r}{y} \\ & =\frac{\sqrt{26}}{-5} \\ & =-\frac{\sqrt{26}}{5} \end{align}$ Then evaluate the secant functions as follows: $\begin{align} & \sec \theta =\frac{r}{x} \\ & =\frac{\sqrt{26}}{-1} \\ & =-\sqrt{26} \end{align}$ And finally evaluate the cotangent functions as follows: $\begin{align} & \cot \theta =\frac{x}{y} \\ & =\frac{-1}{-5} \\ & =\frac{1}{5} \end{align}$
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