Tikz，锚点和交叉点

Question

我正在为 Tikz 使用以下 LaTeX 代码：

    \begin{tikzpicture}[    noeud/.style={draw, circle}, 
                            triangle/.style={isosceles triangle, anchor=apex, 
                                             draw, shape border rotate=90,
                                             minimum size = 1cm}, 
                            scale=1]
    \node (A) at (-1.5, -2) {};
    \node (B) at (1.5, -2) {};
    \node[noeud] (r) at (0, 0) {$r$};
    \node[triangle] at (A) {$A$};
    \node[triangle] at (B) {$B$};
    
    \coordinate(Ar) at (intersection of r and r--A);
    \draw (Ar)--(-1.5, -2);

    \coordinate(Bd) at (intersection of r and r--B);
    \draw (Bd)--(1.5, -2);
    \end{tikzpicture}

我想在节点 r 和两个三角形的顶部之间画一条直线。但是，我无法以可读的方式完成我的 Tikz 代码。

有人知道我的问题是什么吗？

下面是我得到的和我想要得到的图片：

Answer 1

您可以轻松地使用库定位所有内容positioning并使用apex锚点来停止连接。

\documentclass[tikz]{standalone}

\usetikzlibrary{positioning, shapes.geometric}

\begin{document}

\begin{tikzpicture}[%
    noeud/.style={draw, circle}, 
    triangle/.style={isosceles triangle, anchor=apex, 
                    draw, shape border rotate=90,
                  minimum size = 1cm}, 
                            scale=1]
%    \node (A) at (-1.5, -2) {};
%    \node (B) at (1.5, -2) {};
    \node[noeud] (r) at (0, 0) {$r$};
    \node[triangle, below left=2cm and 1cm of r] (A) {$A$};
    \node[triangle, below right=2cm and 1cm of r] (B) {$B$};
    
%    \coordinate(Ar) at (intersection of r and r--A);
    \draw (r)--(A.apex) (r)--(B.apex);

%   \coordinate(Bd) at (intersection of r and r--B);
%    \draw (Bd)--(1.5, -2);
    \end{tikzpicture}
    \end{document}