11. As shown in the figure, the rectangle's edge, is the midpoint, point moves along the edge, and moves with, denote, express the sum of distances from the moving point to two points as a function of, then the graph of is approximately

\begin{figure}[h]
\begin{center}
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\caption{A.}
\end{center}
\end{figure}

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{d02047a7-2e53-46f4-95bc-7a4508088779-2_351_311_1251_733}
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\caption{B.}
\end{center}
\end{figure}

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{d02047a7-2e53-46f4-95bc-7a4508088779-2_341_303_1247_1098}
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\caption{C.}
\end{center}
\end{figure}

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{d02047a7-2e53-46f4-95bc-7a4508088779-2_353_314_1251_1439}
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\caption{D.}
\end{center}
\end{figure}