答案1
\rule
这可以通过简单的命令和包来完成mathtools
。我擅自将\underbrace
s 替换为\underbracket
s,因为我发现它们在这种情况下更具表现力:
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align*}
\begin{gathered}
\overline{\mathrm{AB}} \\[-2.5ex]
\underbracket[0.5pt]{\rule{2cm}{0.8pt}}_{\tfrac{1}{2}} \clap{\rule{0.4em}{0.8pt}}\mkern-3mu \underbracket[0.5pt]{\rule{2cm}{0.8pt}}_{\tfrac{1}{2}}
\end{gathered}
& \qquad
\begin{gathered}
\overline{\mathrm{CD}} \\[-2.5ex]
\underbracket[0.5pt]{\rule{2cm}{0.8pt}}_{\tfrac{1}{2}} \clap{\rule{0.4em}{0.8pt}} \mkern-3mu \underbracket[0.5pt]{\rule{2cm}{0.8pt}}_{\tfrac{1}{2}} \clap{\rule{0.4em}{0.8pt}} \mkern-3mu \underbracket[0.5pt]{\rule{2cm}{0.8pt}}_{\tfrac{1}{2}}
\end{gathered}
\end{align*}
\end{document}