## Functions Modeling Change: A Preparation for Calculus, 5th Edition

Published by Wiley

# Chapter 7 - Trigonometry and Periodic Functions - 7.3 Radians and Arc Length - Exercises and Problems for Section 7.3 - Exercises and Problems - Page 284: 27

#### Answer

$(-5,0)$

#### Work Step by Step

Since $-180^\circ=180^\circ-360^\circ$, $-180^\circ$ is the same as $180^\circ$. Use the fact that a point $r$ units from the origin with an angle $\theta$ from the horizontal is located at $(r\cos\theta,r\sin\theta)$. Using $r=5$ and $\theta=180^\circ$, the point is located at $$(5\cos(180^\circ),5\sin(180^\circ))=(-5,0)$$ Verify these trigonometric values using the unit circle if necessary.

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