\documentclass{article}

\usepackage[latin2]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[magyar]{babel}

\begin{document}

\newcommand{\tg}{\mathop{\mathrm{tg}}\nolimits}
\newcommand{\Trace}{\mathop{\mathrm{Trace}}\limits} % a \limits elhagyható

\end{document}