%%
%% Ein Beispiel der DANTE-Edition
%%
%% 7. Auflage
%%
%% Beispiel 35-00-97 auf Seite 858.
%%
%% Copyright (C) 2016 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.
%%
%%
%% ====
% Show page(s) 1
%%
%%
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{352.81416pt}
\setlength\parindent{0pt}
%StartShownPreambleCommands
\usepackage{pst-eucl,pst-plot}
%StopShownPreambleCommands
\begin{document}
\def\Angle{37}
\def\R{5}
\begin{pspicture}(-\R,-\R)(\R,\R)
\pstGeonode[PointSymbol=none,PosAngle={45,-90},PointNameSep=24pt](\R;\Angle){B}(0,0){O}(\R;0){A}
\pcline[linecolor=lightgray,linewidth=12pt,offset=-6pt,strokeopacity=0.6](O)(A)
\pcline[linecolor=lightgray,linewidth=12pt,offset=6pt,strokeopacity=0.6](O)(B)
\psline(B)(O)(A)
\pstMarkAngle[MarkAngleRadius=1.6,LabelSep=.8]{A}{O}{B}{$\theta$}
\pstGeonode(!3 \Angle\space 2 div PtoC){X}
\color{blue}\psset{linecolor=blue}%
\pstOrtSym{O}{A}{X}[I_1] \psline[linestyle=dotted](X)(I_1)
\newif\ifA \Afalse
\pstFPDiv\No{360}{\Angle}
\multido{\iA=1+1,\iB=2+1}{\numexpr\No-1}{%
\ifA\pstOrtSym{O}{A}{I_\iA}[I_\iB]\else\pstOrtSym{O}{B}{I_\iA}[I_\iB]\fi
\psline[linestyle=dotted](I_\iA)(I_\iB)
\ifA\Afalse\else\Atrue\fi
}%
\color{red}\psset{linecolor=red}%
\pstOrtSym{O}{B}{X}[I_1] \psline[linestyle=dotted](X)(I_1)
\newif\ifA \Atrue
\pstFPDiv\No{360}{\Angle}
\multido{\iA=1+1,\iB=2+1}{\numexpr\No-1}{%
\ifA\pstOrtSym{O}{A}{I_\iA}[I_\iB]\else\pstOrtSym{O}{B}{I_\iA}[I_\iB]\fi
\psline[linestyle=dotted](I_\iA)(I_\iB)
\ifA\Afalse\else\Atrue\fi
}%
\pscircle[linestyle=dotted](O){3}
\end{pspicture}
\end{document}
