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: 55

Answer

The slope of the tangent line at $\theta = \pi/6 $ is equal to $\sqrt 3$

Work Step by Step

1. Write the formula for the slope of the tangent line: $$\frac{dy}{dx} = \frac{\frac{dr}{d\theta}sin(\theta) + rcos(\theta)}{\frac{dr}{d\theta}cos(\theta) - rsin(\theta)} $$ 2. Calculate $\frac{dr}{d\theta}$ and substitute the equation into the formula: $\frac{dr}{d\theta} = \frac{d(2sin(\theta))}{d\theta} = 2cos(\theta)$ $\frac{dy}{dx} = \frac{(2cos(\theta)sin(\theta)) + (2sin(\theta))cos(\theta)}{2cos(\theta)cos(\theta) - (2sin(\theta))sin(\theta)}$ $\frac{dy}{dx} = \frac{2(2cos(\theta)sin(\theta)) }{2(cos^2(\theta) - sin^2(\theta))} = \frac{sin(2\theta)}{cos(2\theta)} = tan(2\theta)$ 3. Calculate the slope at the given $\theta$ value: $\frac{dy}{dx} = tan(2\frac {\pi} 6)= tan(\pi/3) = \sqrt 3$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.