Question

Range of the function $f(x)={\cos }^{-1}\left(\frac{1}{e^x+e^{-x}}\right)$ is

• A. $(0,\pi )$
• B. $\left[\frac{\pi }{6},\frac{\pi }{2}\right)$
• C. $\left[\frac{\pi }{3},\frac{\pi }{2}\right)$
• D. $\left[\frac{\pi }{2},\frac{2\pi }{3}\right)$

Answer 1

Answer: (C)

Correct answer is (c) $\left[\frac{\pi }{3},\frac{\pi }{2}\right)$