\ANG{
%
%%\item
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\begin{minipage}[t]{9cm}
Berechnen Sie den Fl"acheninhalt und den Umfang der folgenden Figur
in Abh"angigkeit von $a$. (Die Mittelpunkte der Kreisb"ogen
sind die Punkte $A$, $B$, $C$ und $D$.)
\end{minipage}
\hskip 0.5 cm
\begin{minipage}[t]{9cm}
\beginpicture
\setcoordinatesystem units <1mm,1mm> point at  0 8
\setplotarea x from -20 to 20, y from -40 to 20
\plot -20 0     20   0 /
\plot -10 -1   -10   1 /
\plot  10 -1    10   1 /
\circulararc 180 degrees from   0   0  center at   -10   0
\circulararc 180 degrees from  20   0  center at    10   0
\circulararc -60 degrees from  20   0  center at   -20   0
\circulararc  60 degrees from -20   0  center at    20   0
\betweenarrows {$a$} from -10 -8  to  10  -8
\put {$A$} at -17 -4 
\put {$B$} at  -7 -4 
\put {$C$} at   7 -4 
\put {$D$} at  17 -4 
\endpicture
\end{minipage}
}
\LSG{        
$U={7\over3} \pi a$, $A=({19\over 12}\pi- {\sqrt{3} \over 2})a^2$
}
