利用角平分线定理定义角平分线上的点，进而实现给定角平分线的绘制

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\input{dingyi.tex}

\begin{document}
\begin{tikzpicture}
    % 定义三角形顶点
    \coordinate (A) at (0,0);
    \coordinate (B) at (4,0);
    \coordinate (C) at (1,3);

    % 绘制三角形
    \draw (A) -- (B) -- (C) -- cycle;

    % 调用自定义角平分线命令（参数：顶点A, 边点B, 边点C, 交点D, 延伸端点E, 样式）
    \jpfx{A}{B}{C}{D}{1.5}{cyan, thick};
    \jpfx{A}{B}{C}{E}{.8}{red, very thick};

    % 标记点（所有点均已定义，无报错）
    \node[below left] at (A) {$A$};
    \node[below right] at (B) {$B$};
    \node[above] at (C) {$C$};
    \node[above] at (D) {$D$};
    \node[above] at(E) {$E$};
\end{tikzpicture}
\end{document}