Tikz，坐标计算错误

Question

我想绘制 3 个从 (m) 开始并计算长度的向量，但出现问题。基本上，我在最后的第 1 行和第 3 行中收到错误或渲染错误（根据不同的尝试）：

\draw[->, very thin] (m) -- ($-155:1*sin(65)$) coordinate (m);
\draw[->, very thin] (m) -- ($-65:1*cos(65)$) coordinate (m);

梅威瑟：

\documentclass{article}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetikzlibrary{calc,patterns,angles,quotes,intersections}
\tikzset{bullet/.style={circle, fill,minimum size=4pt,inner sep=0pt, outer sep=0pt}}

\begin{document}

\begin{tikzpicture}[scale=1,
  interface/.style={
        postaction={draw,decorate,decoration={border,angle=-45,
                    amplitude=0.15cm,segment length=1mm}}},
  ]
  \draw[black,line width=.5pt,interface](1,0)--(-1,0);
  \draw[dotted, thin] (0,0) -- (0,-2.5);
  \coordinate (m) at (-65:2);
  \draw[thin] (0,0) -- (m);
  \begin{scope}
    \clip(-1,0) rectangle (1,-2.5);
    \draw[thin] (0,0) circle(2);
  \end{scope}
  \node[bullet, minimum size=4pt] at (m) {};
  \draw[->, very thin] (m) -- ($-155:1*sin(65)$) coordinate (m);
  \draw[->, very thin] (m) -- (-90:1) coordinate (m);
  \draw[->, very thin] (m) -- ($-65:1*cos(65)$) coordinate (m);
\end{tikzpicture}

\end{document}

Answer 1

如果执行涉及一些括号的计算，则需要使用括号。我也不认为您$在这里需要，因为您只使用极坐标（而不使用坐标计算calc）。

\documentclass{article}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetikzlibrary{calc,patterns,angles,quotes,intersections}
\tikzset{bullet/.style={circle, fill,minimum size=4pt,inner sep=0pt, outer sep=0pt}}

\begin{document}

\begin{tikzpicture}[scale=1,
  interface/.style={
        postaction={draw,decorate,decoration={border,angle=-45,
                    amplitude=0.15cm,segment length=1mm}}},
  ]
  \draw[black,line width=.5pt,interface](1,0)--(-1,0);
  \draw[dotted, thin] (0,0) -- (0,-2.5);
  \coordinate (m) at (-65:2);
  \draw[thin] (0,0) -- (m);
  \begin{scope}
    \clip(-1,0) rectangle (1,-2.5);
    \draw[thin] (0,0) circle(2);
  \end{scope}
  \node[bullet, minimum size=4pt] at (m) {};
  \draw[->, very thin] (m) -- (-155:{1*sin(65)}) coordinate (m);
  \draw[->, very thin] (m) -- (-90:1) coordinate (m);
  \draw[->, very thin] (m) -- (-65:{1*cos(65)}) coordinate (m);
\end{tikzpicture}

\end{document}

此代码重新定义m，即如果你说

\draw[->, very thin] (m) -- (-155:{1*sin(65)}) coordinate (m);

则为m处的坐标(-155:{1*sin(65)})，依此类推。如果您不想这样做，请使用例如（根据您的评论）

\documentclass{article}
\usepackage{tikz}
\usepackage{tkz-euclide}
\usetikzlibrary{patterns}
\tikzset{bullet/.style={circle, fill,minimum size=4pt,inner sep=0pt, outer sep=0pt}}

\begin{document}

\begin{tikzpicture}[scale=1,
  interface/.style={
        postaction={draw,decorate,decoration={border,angle=-45,
                    amplitude=0.15cm,segment length=1mm}}},
  ]
  \draw[black,line width=.5pt,interface](1,0)--(-1,0);
  \draw[dotted, thin] (0,0) -- (0,-2.5);
  \coordinate (m) at (-65:2);
  \draw[thin] (0,0) -- (m);
  \begin{scope}
    \clip(-1,0) rectangle (1,-2.5);
    \draw[thin] (0,0) circle[radius=2];
  \end{scope}
  \node[bullet, minimum size=4pt] at (m) {};
  \draw[->, very thin] (m) -- ++(-155:{1*sin(65)});
  \draw[->, very thin] (m) -- ++(-90:1);
  \draw[->, very thin] (m) -- ++(-65:{1*cos(65)});
\end{tikzpicture}

\end{document}