Mit `pgfplots`. (Ich hoffe ich habe die Frage richtig verstanden)
\documentclass{article}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
\begin{axis}
[
% Plot settings
domain=0:120,
samples=101,
no markers,
smooth,
% Axis settings
axis equal,
axis lines=middle,
enlargelimits=true,
xlabel=$x$,
ylabel=$y$,
xtick=\empty,
ytick=\empty,
]
\def\rb{5}
\def\rr{4}
% Circles
\addplot[blue] ({\rb*cos(x)},{\rb*sin(x)});
\addplot[red,dashed] ({\rr*cos(x)},{\rr*sin(x)});
% Gray lines
\addplot[help lines,->,domain=0:45] ({(\rb+.5)*cos(x)},{(\rb+.5)*sin(x)})
node [above right] {$\theta$};
\addplot[help lines,dashed,domain=0:1] ({x*(\rb+.5)*cos(45)},{x*(\rb+.5)*sin(45)});
\addplot[help lines,dotted,domain=0:1] ({x*\rb*cos(120)},{x*\rb*sin(120)});
% Plot in between
\addplot[black] (
{( \rr + .5*(\rb-\rr)*( 1+cos(5*3/2*(x-60)) ) )*cos(x)},
{( \rr + .5*(\rb-\rr)*( 1+cos(5*3/2*(x-60)) ) )*sin(x)}
);
\end{axis}
\end{tikzpicture}
\end{document}
![alt text][1]
[1]: http://texwelt.de/wissen/upfiles/test_279.pnghttp://texwelt.de/wissen/upfiles/test_280.png
