Ich würde auf das Rotieren der Bögen verzichten und statt dessen Polarkoordinaten verwenden. Für die Teilung sind außerdem eigentlich nur Linien nötig.
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\usepackage[ngerman]{babel}
\usepackage{tikz}
\begin{document}
\begin{figure}[hbt]
\newcommand*\myradius{2.4}
\begin{minipage}[t]{0.48\linewidth}%
\centering
\begin{tikzpicture}%
\fill[yellow,draw=blue](0,0)--(90:\myradius)arc(90:{360+52}:\myradius)--cycle;
\fill[red!20,draw=black,shift={({(90+52)/2}:.2)}](0,0)--(52:\myradius)arc(52:90:\myradius)--cycle;
\draw[red, dotted](current \fill[yellow,draw=blue](0,0)--(90:\myradius)arc(90:412:\myradius)--cycle;
\fill[red!20,draw=black,shift={(71:.2)}]
(0,0)--(52:\myradius)arc(52:90:\myradius)--cycle;
\draw[red,dotted]
(current bounding box.south west) rectangle(current bounding box.north east);
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\caption{Bildunterschrift 1}
\end{minipage}%
\hfill%
\begin{minipage}[t]{0.48\linewidth}%
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\fill[yellow, draw=blue](0,0)--(90:\myradius)arc(90:412:\myradius)--cycle;
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\fill[red!20,draw=black,shift={(71:.2)}]
(0,0)--(52:\myradius)arc(52:90:\myradius)--cycle;
\draw[red,dotted]
(current bounding box.south west)rectangle(current bounding box.north east);
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\caption{Bildunterschrift 1}
\end{minipage}%
\hfill%
\begin{minipage}[t]{0.48\linewidth}%
\centering\begin{tikzpicture}%
\fill[yellow,draw=blue](0,0)--(90:\myradius)arc(90:{360+52}:\myradius)--cycle;
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\fill[red!20,draw=black,shift={(71:.2)}](0,0)--(52:\myradius)arc(52:90:\myradius)--cycle;
\draw[red, dotted](current bounding box.south west)rectangle(current bounding box.north east);
\end{tikzpicture}%
\caption{Bildunterschrift 2}%
\end{minipage}%
\end{figure}
\end{document}
![alt text][1]
[1]: http://texwelt.de/wissen/upfiles/tw_kreisdiagr.PNG
