Bounded Below Real-Valued Function/Examples/Tangent on 0 to pi by 2

Example of Bounded Below Real-Valued Function

The real tangent function on the half-open interval $\hointr 0 {\dfrac \pi 2}$:

$\forall x \in \hointr 0 {\dfrac \pi 2}: \tan x$

is bounded below by $0$, but unbounded above.

Sources

• 1947: James M. Hyslop: Infinite Series (3rd ed.) ... (previous) ... (next): Chapter $\text I$: Functions and Limits: $\S 3$: Bounds of a Function