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使用 tikz 标签角度

tag-icon • tag-icon tikz-pgf
使用 tikz 标签角度

我能够用

\begin{tikzpicture}[thick]
  \draw (0,0)  -- (4,0) node[midway,below]{$f$} -- (4,2) node[midway,right]{$\frac{x}{2}$}-- cycle;
\end{tikzpicture}

现在我想标记三角形的左角，但我不知道该怎么做。

答案1

我的答案显示了如何标记顶点和角度。宏tikzAngleOfLine没有优化

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{calc}

\begin{document}

\newcommand{\tikzAngleOfLine}{\tikz@AngleOfLine}
  \def\tikz@AngleOfLine(#1)(#2)#3{%
  \pgfmathanglebetweenpoints{%
    \pgfpointanchor{#1}{center}}{%
    \pgfpointanchor{#2}{center}}
  \pgfmathsetmacro{#3}{\pgfmathresult}%
  }

  \begin{tikzpicture}
    \coordinate (A) at (1,1);
    \coordinate (B) at ($(A)+(25:3)$);
    \coordinate (C) at ($(A)+(100:5)$);
    \draw (A) node[left]{$A$} -- (B) node[right]{$B$}node[midway,below]{$c$} -- (C)node[above]{$C$}node[midway,above]{$a$} -- (A)node[midway,left]{$b$};

    \tikzAngleOfLine(A)(B){\AngleStart}
    \tikzAngleOfLine(A)(C){\AngleEnd}
    \draw[red,<->] (A)+(\AngleStart:2cm) arc (\AngleStart:\AngleEnd:2 cm);
    \node[circle,fill=green] at ($(A)+({(\AngleStart+\AngleEnd)/2}:1 cm)$) {$\alpha$};
\end{tikzpicture}
\end{document}

在此处输入图片描述

答案2

以下是使用 TikZ 3.0 的解决方案：

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{quotes,angles}
\begin{document}
\begin{tikzpicture}
  \draw
  (3,-1) coordinate (a) node[right] {a}
  -- (0,0) coordinate (b) node[left] {b}
  -- (2,2) coordinate (c) node[above right] {c}
  pic["$\alpha$",draw=orange,<->,angle eccentricity=1.2,angle radius=1cm] {angle=a--b--c};
\end{tikzpicture}
\end{document}

在此处输入图片描述

答案3

我基于上述 Alain Matthes 的出色回答，定义了一个更直接的宏。我还提供了其用例的示例。

\newcommand{\tikzAngleOfLine}{\tikz@AngleOfLine}                               
  \def\tikz@AngleOfLine(#1)(#2)#3{%                                            
  \pgfmathanglebetweenpoints{%                                                 
    \pgfpointanchor{#1}{center}}{%                                             
    \pgfpointanchor{#2}{center}}                                               
  \pgfmathsetmacro{#3}{\pgfmathresult}%                                        
  }                                                                            
\newcommand{\tikzMarkAngle}[3]{                                                
\tikzAngleOfLine#1#2{\AngleStart}                                              
\tikzAngleOfLine#1#3{\AngleEnd}                                                
\draw #1+(\AngleStart:0.15cm) arc (\AngleStart:\AngleEnd:0.15cm);              
}                                                                              

\begin{tikzpicture}[scale=4,line width=1pt]                                    
  \coordinate (B) at (0,0);                                                    
  \coordinate (C) at (1,0);                                                    
  \coordinate (A) at (0.5,1.5);                                                
  \draw (A) -- (B) -- (C) -- cycle;                                            
  \node [below left]  at (B) {B};                                              
  \node [below right] at (C) {C};                                              
  \node [above]       at (A) {A};                                              
  \coordinate (D) at (barycentric cs:A=0.5 ,C=0.5);                            
  \node [above right] at (D) {D};                                              
  \draw (B) -- (D);                                                            

  \tikzAngleOfLine(A)(C){\AngleStart}                                          
  \tikzAngleOfLine(A)(B){\AngleEnd}                                            
   \draw (A)+(\AngleStart:0.15cm) arc (\AngleStart:\AngleEnd:0.15cm);          

  \tikzMarkAngle{(C)}{(B)}{(A)}                                                
  \tikzMarkAngle{(D)}{(A)}{(B)}                                                
\end{tikzpicture}

以下是使用示例宏。

使用示例

我还在下面提供了一个稍微更复杂的例子。

另一个示例用法

\newcommand{\tikzAngleOfLine}{\tikz@AngleOfLine}
  \def\tikz@AngleOfLine(#1)(#2)#3{%
  \pgfmathanglebetweenpoints{%
    \pgfpointanchor{#1}{center}}{%
    \pgfpointanchor{#2}{center}}
  \pgfmathsetmacro{#3}{\pgfmathresult}%
  }
\newcommand{\tikzMarkAngle}[4][0.15cm]{
\tikzAngleOfLine#2#3{\AngleStart}
\tikzAngleOfLine#2#4{\AngleEnd}
\draw[<->] #2+(\AngleStart:#1) arc (\AngleStart:\AngleEnd:#1);
}

\begin{tikzpicture}[scale=4,line width=1pt]
  \coordinate (B) at (0,0);
  \coordinate (C) at (1,0);
  \coordinate (A) at (0.5,1.5);
  \draw (A) -- (B) -- (C) -- cycle;
  \node [below left]  at (B) {B}; 
  \node [below right] at (C) {C}; 
  \node [above]       at (A) {A};
  \coordinate (D) at (barycentric cs:A=0.5 ,C=0.5);
  \coordinate (E) at (barycentric cs:A=0.40 ,B=0.60);
  \node [above right] at (D) {D};
  \node [above left] at (E) {E};
  \draw (B) -- (D);
  \draw (C) -- (E);
  \draw (E) -- (D);

  \tikzMarkAngle{(A)}{(B)}{(C)}

  \node at ($(A)+(-90:0.23)$) {$20^\circ$};
  \tikzMarkAngle{(B)}{(D)}{(C)}
  \node at ($(B)+(25:0.23)$) {$60^\circ$};
  \tikzMarkAngle{(C)}{(B)}{(E)}
  \node at ($(C)+(155:0.23)$) {$50^\circ$};

  \begin{scope}[color=orange]
  \tikzMarkAngle{(D)}{(E)}{(B)}
  \node at ($(D)+(-20:0.15)$) {?=$30^\circ$};
  \end{scope}

  \tikzMarkAngle{(B)}{(A)}{(D)}
  \node at ($(B)+(55:0.23)$) {$20^\circ$};
  \tikzMarkAngle{(C)}{(E)}{(D)}
  \node at ($(C)+(120:0.23)$) {$30^\circ$};

  \coordinate (F) at (barycentric cs:A=0.50 ,B=0.50);
  \node [above left] at (F) {F};
  \draw (F) -- (D);
  \draw (C) -- (F);

  \coordinate (G) at (intersection of D--B and C--F);
  \node [above] at (G) {G};

 \draw (E) -- (G);
 \begin{scope}[color=blue]
   \tikzMarkAngle{(G)}{(F)}{(E)}
   \node at ($(G)+(145:0.20)$) {$40^\circ$};
   \tikzMarkAngle[0.07cm]{(F)}{(E)}{(G)}
   \node at ($(F)+(-175:0.10)$) {$40^\circ$};
   \tikzMarkAngle{(D)}{(A)}{(F)}
   \node at ($(D)+(135:0.22)$) {$80^\circ$};
 \end{scope}
\end{tikzpicture}

答案4

您可以在三角形的起始处插入一个节点，即(0,0)，并在其左侧放置一个标签node[left]{$A$}。完整示例：

\documentclass{article}

\usepackage{tikz}

\begin{document}

\begin{tikzpicture}[thick]
  \draw (0,0) node[left]{$A$}  -- (4,0) node[midway,below]{$f$} -- (4,2) node[midway,right]{$\frac{x}{2}$}-- cycle;
\end{tikzpicture}

\end{document}

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