I am trying to make a presentation in beamer. However when I include letters in the math environment I get the following error message:
!pdfTeX error: pdflatex (file mathkerncmssi8): Font mathkerncmssi8 at 525 not f
ound
==> Fatal error occurred, no output PDF file produced!
What am I doing wrong?
\documentclass[10pt]{beamer}
\usetheme{Copenhagen}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{graphicx}
\title{Test}
\begin{document}
\begin{frame}
\titlepage
\end{frame}
\begin{frame}
$r_d$
\end{frame}
\end{document}
