Answer
$0$
Work Step by Step
Inverse Secant Function:
$y=\sec^{-1}x$ or $y=$ arcsec $x$ means that
$x=\sec y$, for $0 \leq y \leq \pi, y\displaystyle \neq\frac{\pi}{2}$.
----------------
$\displaystyle \sec 0=\frac{1}{\cos 0}=\frac{1}{1}=1,$
and $0 \leq $0$ \leq \pi,$ 0$\displaystyle \neq\frac{\pi}{2}$,
so
$y=\sec^{-1}1=0$