
I wrote this until now:
Code: Select all
\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\makeatletter
\newcommand\mathcircled[1]{%
\mathpalette\@mathcircled{#1}%
}
\newcommand\@mathcircled[2]{%
\tikz[baseline=(math.base)] \node[draw,circle,inner sep=1pt] (math) {$\m@th#1#2$};%
}
\makeatother
\begin{document}
\[\lim_{x\to\infty} \frac{\sin x}{x}= \mathcircled{\frac{\sin x}{x}}=1\]
\end{document}
