Working Example:
Code: Select all
\documentclass[draft]{article}
\begin{document}
\begin{figure}
it is ok
\caption{$\triangle OKE$}
\end{figure}
\end{document}
Code: Select all
\documentclass[draft]{article}
\begin{document}
\begin{figure}
it is not ok
\caption{$\angle NOT$}
\end{figure}
\end{document}