\documentclass[border=5cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{matrix, positioning, calc}
\begin{document}
\tikzset{every matrix/.style={matrix of math nodes, left delimiter=|, right delimiter=|, column sep=1.5em, row sep=1.5em, nodes={inner sep=0.3ex}}}
\newcommand{\mycenter}[4]{ \path (#1)--coordinate[pos=0.5](a)(#2) (#1)--coordinate[pos=0.5](b)(#3); \coordinate (#4) at (b-|a); }
\begin{tikzpicture}[rounded corners, text=black, draw=gray!70]
\matrix (Mb) {
a_{11} & a_{12} & a_{13} \\
a_{21} & a_{22} & a_{23} \\
a_{31} & a_{32} & a_{33} \\
};
\draw[red] (Mb-1-1)--(Mb-2-2)--(Mb-3-3);
\mycenter{Mb-1-2}{Mb-1-3}{Mb-2-2}{myc} \mycenter{Mb-2-2}{Mb-2-3}{Mb-3-2}{myc2}
\draw[red] (Mb-1-2)--(Mb-2-3)--($(Mb-3-2)!2!(Mb-3-3)$)--($(myc)!3!(myc2)$) coordinate(x2)--(Mb-3-1);
\coordinate (a14) at ($(Mb-1-2)!2!(Mb-1-3)$); \mycenter{Mb-1-3}{a14}{Mb-2-3}{myd} \coordinate (myd2) at (myc2 -| myd);
\draw[red] (Mb-2-1)--(Mb-3-2)--($(myd)!3!(myd2)$) coordinate(x1)--($(Mb-3-2)!3!(Mb-3-3)$)--(Mb-1-3);
\draw[densely dashed,blue] (Mb-1-3)--(Mb-2-2)--(Mb-3-1);
\coordinate (x3) at ($(x1)!2!(x2)$); \coordinate (x4) at ($(x1)!3!(x2)$);
\draw[densely dashed,blue] (Mb-1-2)--(Mb-2-1)--($(Mb-3-2)!2!(Mb-3-1)$)--(x3)--(Mb-3-3);
\draw[densely dashed,blue] (Mb-2-3)--(Mb-3-2)--(x4)--($(Mb-3-2)!3!(Mb-3-1)$)--(Mb-1-1);
\end{tikzpicture}
\end{document}
一模一样的问题,图都是一样的
https://www.zhihu.com/question/525613625/answer/2420699577
问 三阶行列式计算图解如何画?