[Tex/LaTex] \displaystyle for a part of the document

Question

Is there a way to use \displaystyle for a part of my document? I do not want to change everywhere the inline math sizes, on the other hand it is a bit tedious to write everywhere (in a list of examples might be 60 times) \displaystyle.

In order to give you a minimal example:

I would like to typeset the following code without writing in every line \displaystyle.

\begin{enumerate}   
            \item $\displaystyle \sin \frac{1}{x},\quad x\in (0,1]$
            \item $\displaystyle \frac{1}{\sin x},\quad x\in \left[\frac{\pi}{6},\frac{5\pi}{6}\right]$
            \item $\displaystyle \frac{x}{\sin x},\quad x\in \left[\frac{\pi}{6},\frac{\pi}{2}\right]$
\end{enumerate}

Thanks a lot!

Answer 1

Use \everymath{\displaystyle}. To make it local, put it inside a group:

\documentclass{article}

\begin{document}
Text style: $\frac{a}{b}$

\bgroup
\everymath{\displaystyle}
Display style: $\frac{a}{b}$
\egroup

And back: $\frac{a}{b}$
\end{document}