答案1
这里至少有一些东西可以供您玩。我还没有添加图片中的所有内容,您必须弄清楚。
\documentclass[tikz,margin=4mm]{standalone}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}
\def\xEpsilon{1}
\def\cRadius{5}
\coordinate (R) at (\cRadius,0);
\coordinate (mR) at (-\cRadius,0);
\coordinate (O) at (0,0);
\coordinate (x) at ($(O)!0.6!(R)$);
\coordinate (xme) at ($(x)+(-\xEpsilon,0)$);
\coordinate (xpe) at ($(x)+(\xEpsilon,0)$);
\begin{scope}[red,very thick]
\draw (R) arc [start angle=0,end angle=180,radius=5]
-- (O)
-- (xme) arc [start angle=180,end angle=0,radius=\xEpsilon] node[pos=0.5,above,black] {$\gamma_{\varepsilon}$}
-- cycle
;
\end{scope}
\draw ($(x)+(0,0.1)$) -- ++(0,-0.2) node[below] {\strut$x$};
\draw ($(R)+(0,0.1)$) -- ++(0,-0.2) node[below] {\strut$R$};
\draw ($(mR)+(0,0.1)$) -- ++(0,-0.2) node[below] {\strut$-R$};
\draw ($(mR)+(-0.2,0)$) -- ($(R)+(0.2,0)$);
\draw ($(O)+(0,-0.2)$) -- ++ (0,\cRadius + 0.4);
\end{tikzpicture}
\end{document}