![如何在曲线路径上的三个等距点处绘制等长的切线?](https://linux22.com/image/473517/%E5%A6%82%E4%BD%95%E5%9C%A8%E6%9B%B2%E7%BA%BF%E8%B7%AF%E5%BE%84%E4%B8%8A%E7%9A%84%E4%B8%89%E4%B8%AA%E7%AD%89%E8%B7%9D%E7%82%B9%E5%A4%84%E7%BB%98%E5%88%B6%E7%AD%89%E9%95%BF%E7%9A%84%E5%88%87%E7%BA%BF%EF%BC%9F.png)
就像下面的弯曲三角形
我所能画的只是 MWE。
\documentclass[tikz]{standalone}
\begin{tikzpicture}
\draw (0,0) -- (4.5,0) -- (6,2) -- (1.5,2) -- cycle;
\draw [xshift=3cm,yshift=1cm] (0,0) ellipse (1.2 and .6);
\draw [xshift=3cm,yshift=1cm,->,teal] (0,.6) -- (.6,.6);
\draw [xshift=3cm,yshift=1cm,->,teal] (1.2,0) -- (1.9,0);
\draw [xshift=3cm,yshift=1cm,->,teal] (0,-.6) -- (.6,-.6);
\draw [xshift=3cm,yshift=1cm,->,teal] ({-1.2*cos(30)},{-.6*sin(30)}) --++ (.6,0) node [above] {$v^a$};
\draw [xshift=3cm,yshift=1cm,->,teal] ({-1.2*cos(30)},{.6*sin(30)}) --++ (.6,0);
\shade [xshift=3cm,yshift=1cm,ball color=teal] (-1.2,0) circle (.06);
\end{tikzpicture}