\ANG{
\begin{minipage}[t]{9cm}
%Oberfl"ache von Kugel, Zylinder und Kegel, BIGTEX verwenden
Berechnen Sie die Gesamtoberfl"ache des Rotationsk"orpers in
Abh"angigkeit von $a$ 
und $\pi$!
\end{minipage}
\hfill
\begin{minipage}[t]{3.8cm}
\makebox[0cm]{}\\
\beginpicture

\setcoordinatesystem units <1mm,1mm> point at 0 0
\setplotarea x from -5 to 35, y from -10 to 60
\unitlength1mm
\normalsize
\setquadratic
\vshade 0 0 20 5 0.635 20 10 2.679 20 /
\hshade 2.679 10 10  10 10 17.322 20 10 20 /
\circulararc 90 degrees from 0 0 center at 0 20

\setlinear
\vshade 0 20 20 20 20 50 /
\plot 0 20 20 20 20 50 0 20  /

\setdashes <0.5mm> 
\plot 0 -5 0 55 /
\setdots <2mm>
\plot 0 0 25 0 /
\put {Achse} [Bl] at -5 57

\betweenarrows {5a} [l] <1mm,0pt> from 20 0 to 20 50
\betweenarrows {2a} [BL] <0pt,0pt> from 0 50  to 20 50

\endpicture
\end{minipage}
}
\LSG{
$O=a^2 \pi (20+2 \sqrt{13})$
}
