Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 10 - Parametric Equations and Polar Coordinates - 10.3 Exercises - Page 688: 73

Answer

The graphs were obtained by rotating $r= 1+\sin\theta.$ In general, the graph $r=f(\theta-\alpha)$ is obtained by rotating the graph of $r=f(\theta)$ by the angle $\alpha$, counterclockwise.

Work Step by Step

Graphing the three curves, also graph the lines $\displaystyle \theta=\frac{\pi}{6}$ and $\displaystyle \theta=\frac{\pi}{3}$. Note the point A on $ r=1+\sin\theta$ (black curve). Rotating it by $\displaystyle \frac{\pi}{6}$, we have its corresponding point on $ r=1+\sin\theta$ (blue). Also, we note that the red curve is obtained by rotating the black curve by $\displaystyle \frac{\pi}{3}$, counterclockwise. In general, the graph $r=f(\theta-\alpha)$ is obtained by rotating the graph of $r=f(\theta)$ by the angle $\alpha$, counterclockwise.
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