$\{0\}$

$[-1,1]$

$(-\infty,-1) \cup(1, \infty)$

$(-1,0) \cup(0,1)$

no solution

only one solution

two solutions

more than two solutions

$\frac{1}{\sqrt{3}}$

$\sqrt{3}$

1

$3 / 7$

$\operatorname{sech}^{-1}\left(\frac{1}{3}\right)$

$\operatorname{cosech}^{-1}\left(\frac{1}{3}\right)$

$\cosh ^{-1}\left(\frac{4}{3}\right)$

$\sinh ^{-1}\left(\frac{3}{4}\right)$