%% 
%%  Ein DANTE-Edition Beispiel
%% 
%%  Beispiel 04-15-2 auf Seite 109.
%% 
%%  Copyright (C) 2010 Voss
%% 
%%  It may be distributed and/or modified under the conditions
%%  of the LaTeX Project Public License, either version 1.3
%%  of this license or (at your option) any later version.
%% 
%%  See http://www.latex-project.org/lppl.txt for details.
%% 

% Show page(s) 1

\PassOptionsToClass{}{beamer}
\documentclass{beamer}
\usepackage[utf8]{inputenc}


\usetheme{Hannover}


\begin{document}
\begin{frame}{Pythagoras}
\begin{align}
 c^2 &= a^2+b^2     \label{Pythagoras}\\
 c^2 &= a^2+b^2-2ab\cos\gamma
                    \label{Cosinussatz}
\end{align}
foo \uncover<2>{bar}

\only<3>{%
  Ohne Overlayspezifikation sinnlos!%
  \label<3>{Marke}}
\end{frame}
\end{document}