## Calculus (3rd Edition)

Since $$\lim _{x \rightarrow \frac{\pi}{2}-} \tan x=\infty$$ and $$\lim _{x \rightarrow \frac{\pi}{2}+} \tan x=-\infty$$ Then $\lim _{x \rightarrow \frac{\pi}{2} } \tan x$ does not exist.