\ANG{
% 9/Geometrie/Strahlensatz 
%%\item
Berechne jeweils $x$ und $y$:\\[2mm]
(a)
\raisebox{-14mm}{\parbox[t]{4.2cm}{
\begin {scriptsize}
\unitlength=1mm
\beginpicture 
\setcoordinatesystem units <1mm,1mm> 
\setplotarea x from -20 to 30, y from -15 to 15 
\inboundscheckon 
\setlinear 
\plot -20 5  30 -7.5 /  
\plot -20 -10  30 15 /  
\plot -17.5 -10  -15 5 /  
\plot 20 -15  25 15 /  
\put {$2$} at -18 -2 
\put {$3$} at -7.5 4 
\put {$x$} at -7.5 -6 
\put {$y$} at 25 2 
\put {$4$} at 12 8 
\put {$5$} at 11 -5 
\endpicture 
\end {scriptsize} }}
\qquad (b)
\raisebox{-14mm}{\parbox[t]{4.2cm}{
\begin {scriptsize}
\unitlength=1mm
\beginpicture 
\setcoordinatesystem units <1mm,1mm> 
\setplotarea x from -20 to 30, y from -15 to 15 
\inboundscheckon 
\setlinear 
\plot -20 5  30 -7.5 /  
\plot -20 -10  30 15 /  
\plot -17.5 -10  -15 5 /  
\plot 20 -15  25 15 /  
\put {$x$} at -18 -2 
\put {$3$} at -7.5 4 
\put {$x$} at -7.5 -6 
\put {$y$} at 25 2 
\put {$12$} at 12 8 
\put {$x$} at 11 -5 
\endpicture 
\end {scriptsize} }}

}
\LSG{ 
(a) $\D x=2,4\,,\quad y=\frac{10}{3}$\qquad 
(b) $x=6\,,\quad y=12$
}
