If we the function $f(x)$ in the interval $x \in [\frac{\pi}{4}, \frac{7\pi}{4}]$, will $\frac{\pi}{4}$ be one of the local minima and $\frac{7\pi}{4}$ one of the local maxima?
Also if the interval was $x \in (\frac{\pi}{4}, \frac{7\pi}{4})$, will the number just little more than $\frac{\pi}{4}$ be one of the local minima and number just little less than $\frac{7\pi}{4}$ one of the local maxima? If yes, is there anyway to denote that number using limits or something?