The Secant Function and Inverse Secant Function

$\sec x=\dfrac1{\cos x}$ is defined wherever $\cos x\ne0$, so its domain is $\mathbb{R}\setminus\left\{(2n+1)\tfrac{\pi}2:n\in\mathbb{Z}\right\}$. Since $-1\le\cos x\le1$, $\sec x$ never lands strictly between $-1$ and $1$, so its range is $(-\infty,-1]\cup[1,\infty)$ — the same range as cosecant. Secant has NEITHER a maximum nor a minimum, is periodic with period $2 …