# Chapter 2 - The Derivative - 2.5 Derivatives of Trigonometric Functions - Exercises Set 2.5 - Page 152: 37

The statement is true.

#### Work Step by Step

If we divide both sides of equality $f(x)\cos x=\sin x$ with $\cos(x)$ we get that $f(x)=\frac{\sin x}{\cos x}=\tan x$. Now it is easy to see that $$f'(x)=(\tan x)'=\sec^2x$$ So, the statement is true.

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.