%% 
%%  The LaTeX Graphics Companion, 2ed (first printing May 2007)
%% 
%%  Example D-6-5 on page .
%% 
%%  Copyright (C) 2007 Michel Goossens, Frank Mittelbach, Denis Roegel, Sebastian Rahtz, Herbert Vo\ss 
%% 
%%  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{ttctexaplate}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{413.44133pt}
\StartShownPreambleCommands
\usepackage[dvipsnames]{pstricks}
\usepackage{pst-eucl}
\StopShownPreambleCommands
\begin{document}
\psset{unit=2cm}
\pspicture(-2.5,-2)(2,2.5)
\pstTriangle[linewidth=1pt,fillstyle=solid,fillcolor=black!15](-2,-1){A}(1,2){B}(2,0){C}
% les médiatrices
{% hold settings local
  \psset{linestyle=none, PointSymbolB=none}
  \pstMediatorAB[PointNameB={}]{A}{B}{K}{KP}\uput{50pt}[-45](KP){KP}
  \pstMediatorAB[PointNameB={}]{C}{A}{J}{JP}\uput{-50pt}[100](JP){JP}
  \pstMediatorAB[PosAngleA=75,PointNameB={}]{B}{C}{I}{IP}\uput{-5pt}[210](IP){IP}
}% end of local
\pstInterLL[PointSymbol=square, PosAngle=-170]{I}{IP}{J}{JP}{O}
{%
  \psset{nodesep=-.8, linecolor=[cmyk]{0.8,0,0.8,0}}
  \pstLineAB{O}{I}\pstLineAB{O}{J}\pstLineAB{O}{K}
}%
\pstCircleOA[linecolor={[cmyk]{0,1,1,0}}]{O}{A}
% pour que le symbol de O soit sur et non sous les droites
\psdot[dotstyle=square](O)
% les hauteurs et l'orthocentre
\pstProjection{B}{A}{C}{C'}
\pstProjection{B}{C}{A}{A'}
\pstProjection{A}{C}{B}{B'}
\psset{linecolor=blue}\ncline{A}{A'}\ncline{C}{C'}\ncline{B}{B'}
\pstInterLL[PointSymbol=square]{A}{A'}{B}{B'}{H}
% les médianes et le centre de gravité
\psset{linecolor=magenta}
\ncline{A}{I}
\ncline{C}{K}
\ncline{B}{J}
\pstCGravABC[PointSymbol=square, PosAngle=95]{A}{B}{C}{G}
\endpspicture
\end{document}