tikz 中的角度看起来更长

Question

红色角标的尖端较大。如何修复此问题。

\begin{tikzpicture}[thick, scale = 1.5, transform shape]
\coordinate (origo) at (0,0); 
\draw (0,0) ellipse (2cm and 1cm);
\draw [->] (0,0) -- (-0.9,-0.9);
  \node (a) {};
  \node (A)[below left = 0.7cm and 0.7cm of a] {$x$};
 \draw [->, color = blue] (0,0) -- (0.5,-0.98);  
   \node (B)[below right = 0.8cm and 0.15cm of a] {$x_1,x_2$};
\pic [draw = red, text = blue, ->, "$\Phi$", angle eccentricity = 1.5] {angle = A--origo--B};
\end{tikzpicture}

Answer 1

坐标定义存在一些不匹配的情况。请尝试以下操作：

\documentclass[border=3mm,tikz]{standalone}
\usetikzlibrary{angles, quotes, positioning}

    \begin{document}
\begin{tikzpicture}[thick, scale = 1.5, transform shape]
    \coordinate (O) at (0,0);
    \coordinate[label=below  left:$x$]          (A) at (-0.9,-0.9);
    \coordinate[label=below right:{$x_1,x_2$}]  (B) at (0.5,-0.98);
\draw (O) ellipse (2cm and 1cm);
    \draw [->] (O) -- (A);
    \draw [->] (O) -- (B);
\pic [draw=red, text=blue,->, "$\Phi$", angle eccentricity=1.5] {angle = A--O--B};\end{tikzpicture}
    \end{document}

导致您出现问题的原因是，您考虑的节点 (a) 和 (b) 的中心pic与您的箭头不对齐。节点“b”较宽，因此坐标略微向右移动。为了消除此偏移，我选择真实坐标（即大小为零的节点），对于坐标标签，使用label坐标中的选项。

Answer 2

Aluamplib替代方案，仅用于比较。使用 进行编译lualatex。

\documentclass[border=5mm]{standalone}
\usepackage{unicode-math}
\setmathfont{Tex Gyre Termes Math}
\usepackage{luamplib}
\begin{document}
\mplibtextextlabel{enable}
\begin{mplibcode}
  beginfig(1);
    path ellipse, arc, arrow[]; 
    ellipse = fullcircle xscaled 4cm yscaled 2cm;
    arrow1 = origin -- point 5.2 of ellipse;
    arrow2 = origin -- point 6.3 of ellipse;
    arc = ellipse scaled 1/2 cutbefore arrow1 cutafter arrow2;
    draw ellipse;
    drawarrow arrow1;
    drawarrow arrow2 withcolor .67 blue;
    drawarrow arc    withcolor .53 red;
    label.llft("$x$",        point 1 of arrow1);
    label.lrt ("$x_1, x_2$", point 1 of arrow2);
    label.bot ("$Φ$",        point 1/2 of arc) withcolor .67 blue;
  endfig;
\end{mplibcode}
\end{document}