Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 5 - Trigonometric Identities - Section 5.3 Sum and Difference Identities for Cosine - 5.3 Exercises - Page 218: 34


$\tan$ is to be filled in the blank.

Work Step by Step

$$A72^\circ=\cot18^\circ\hspace{1cm}(1)$$ We notice that $$72^\circ+18^\circ=90^\circ$$ That means we can rewrite $(1)$ as $$A72^\circ=\cot(90-72^\circ)\hspace{1cm}(1)$$ Now from the Cofunction Identity: $$\tan\theta=\cot(90^\circ-\theta)$$ So $$A=\tan$$ In other words, we fill in the blank with $\tan$.
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.