半圆拱，直底

Question

我正在尝试调整之前问题提供的解决方案使用 TikZ 制作的平底半圆形拱形图像使圆弧成为一个精确的半圆。

这是我目前为止得到的最好的答案。如何关闭右侧对称的内弧（如左侧所示）（右半部分有很多杂乱），而不是连接到 f。底部应该是矩形，顶部延伸到外拱。如何消除 1-a 线？非常感谢您的帮助/建议。

\documentclass[tikz,border=2pt]{standalone}
\begin{document}

\begin{tikzpicture}[outer sep=.2cm,inner sep=0pt,scale=1.5,line width=.7pt,line join=round]
\draw (180:3)coordinate[label=left:a](a) arc (180:0:3) coordinate[label=right:f](b)--(30:2.5)coordinate[label=left:](c) arc (30:170:2.5)coordinate[label=above right:1](d)--cycle;
\draw (a)--(2.6,0)coordinate[label=right:g](g)|-coordinate[label=above:7](e) (d);
\draw (c)--(e) (b)--(g);
\foreach \ang/\num/\lett in {150/2/b,120/3/c,90/4/d,60/5/e,30/6/k}{
\draw (\ang:2.5)--(\ang:3) node at (\ang:2.3) {\num};
\node at (\ang:3.2) {\lett};
}
\coordinate[label=below:h] (o) at (0,0);
\draw (o)--(d-|o)node[above]{8};
\end{tikzpicture}

\end{document}

Answer 1

\documentclass[tikz,border=2pt]{standalone}
\begin{document}

\begin{tikzpicture}[outer sep=.2cm,inner sep=0pt,scale=1.5,line width=.7pt,line join=round]
\draw (180:3)coordinate[label=left:a](a) arc (180:0:3) coordinate[label=right:g](b)--(10:2.5)coordinate[label=above left:7](c) arc (10:170:2.5)coordinate[label=above right:1](d)--cycle;
\draw (a)--(3,0)--(c)--(d);
\foreach \ang/\num/\lett in {150/2/b,120/3/c,90/4/d,60/5/e,30/6/f}{
\draw (\ang:2.5)--(\ang:3) node at (\ang:2.3) {\num};
\node at (\ang:3.2) {\lett};
}
\coordinate[label=below:h] (o) at (0,0);
\draw (o)--(d-|o)node[above]{8};
\end{tikzpicture}

\end{document}

更新

底座为半矩形：

\documentclass[tikz,border=2pt]{standalone}
\begin{document}

\begin{tikzpicture}[outer sep=.2cm,inner sep=0pt,scale=1.5,line width=.7pt,line join=round]
\begin{scope}
\path[draw,clip] (180:3)coordinate(a) arc (180:0:3) coordinate[label=right:g](g)--cycle;
\draw(10:2.5)coordinate[label=above left:7](c) arc (10:170:2.5)coordinate[label=above right:1](d);
\draw[shorten >=-2cm, shorten <=-2cm](c)--(d);
\end{scope}

\foreach \ang/\num/\lett in {150/2/b,120/3/c,90/4/d,60/5/e,30/6/f}{
\draw (\ang:2.5)--(\ang:3) node at (\ang:2.3) {\num};
\node at (\ang:3.2) {\lett};
}
\coordinate[label=below:h] (o) at (0,0) node[left]at(a){a} node[right]at(g){g};
\draw (o)--(d-|o)node[above]{8};
\end{tikzpicture}
\end{document}