%% 
%%  Der Mathematiksatz mit LaTeX, 1. Auflage 2009
%% 
%%  Example 10-7-4 on page 225.
%% 
%%  Copyright (C) 2009 Herbert 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.
%% 

\documentclass[]{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{170.59192pt}
\AtBeginDocument{\setlength\parindent{0pt}}
\StartShownPreambleCommands

\StopShownPreambleCommands
\begin{document}
\begin{itemize}
\item Erste Funktion: \\
  $P_1 = \displaystyle\sum_a \in A$
\item Noch eine andere Funktion: \\
  $\sin\left(P_1\right) = \mathrm{konst.}$
\item Oder etwas anderes: \\
  $P_{3}+P_{2}-P_{1} = 0$
\end{itemize}%
\end{document}