Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 3 - Applications of Differentiation - 3.9 Antiderivatives - 3.9 Exercises - Page 283: 33

Answer

$$ f^{\prime}(t)=\sec t(\sec t+\tan t),\quad -\frac{\pi}{2} \lt t \lt \frac{\pi}{2}, \quad f(\frac{\pi}{4})=-1 $$ The required function is $$ f(t)=\tan t+\sec t+-2-\sqrt {2} $$

Work Step by Step

$$ f^{\prime}(t)=\sec t(\sec t+\tan t),\quad -\frac{\pi}{2} \lt t \lt \frac{\pi}{2}, \quad f(\frac{\pi}{4})=-1 $$ can be written as the following: $$ f^{\prime}(t)=\sec t(\sec t+\tan t)=\sec ^{2} t+\sec t \tan t $$ The general anti-derivative of $ f^{\prime}(t)=\sec t(\sec t+\tan t) $ is $$ f(t)=\tan t+\sec t+C $$ To determine C we use the fact that $f(\frac{\pi}{4})=-1$: $$ f(\frac{\pi}{4})=\tan (\frac{\pi}{4})+\sec(\frac{\pi}{4})+C =-1 $$ $ \Rightarrow $ $$ 1+\sqrt {2}+C=-1\quad \Rightarrow \quad C=-2-\sqrt {2}, $$ so $$ f(t)=\tan t+\sec t-2-\sqrt {2} $$
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.