\documentclass[a4paper,12pt]{report}
\usepackage{german,pstricks,pst-node,pst-tree}
\usepackage[latin1]{inputenc}
\begin{document}

\psset{unit=1cm}
\hbox{
\pspicture(0,0)(8,5)
 \rput(1,2){\rnode{A}{Gleichung}}
 \rput(4,0.5){\ovalnode{B}{sichtbar}}
 \rput(6,3){\rnode{C}{Kreis}}
 \rput(7,4.5){\rnode{D}{$x^2+y^2=r^2$}}
 \ncline{->}{A}{D}
 \ncarc{->}{C}{D} \Bput{\footnotesize Beziehung}
 \ncarc{->}{D}{C}
 \nccurve[angleA=240, angleB=90,linestyle=dotted]
   {->}{C}{B}
\endpspicture\hfil
\pstree[treemode=R,levelsep=1cm,radius=2pt]
 {\Tcircle{root}}
 { \pstree{\TC*}{ \Tr{A}  \Tr{B}  \Tr{C} }
   \pstree{\TC*}
     { \pstree{\TC*}{\Tr{$A_1$}  \Tr{$A_2$}}
       \pstree{\TC*}{\Tr{$B_1$}  \Tr{$B_2$}}
     }
   \pstree[treemode=D]{\TC}
     {\TR{$x^2$}  \TR{$y_a^2$}  \TR{$\frac{1}{x+y}$}
     }
 }
}

\end{document}