几何绘图：着色弧

Question

我需要将弧 BC 涂成红色，并将点 D 和 C 涂成较暗的颜色。有人知道怎么做吗？

\documentclass[10pt]{article}
\usepackage[utf8]{inputenc}
\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\pagestyle{empty}
\begin{document}
\definecolor{qqttzz}{rgb}{0,0.2,0.6}
\definecolor{ttqqqq}{rgb}{0.2,0,0}
\definecolor{xdxdff}{rgb}{0.49,0.49,1}
\definecolor{qqqqff}{rgb}{0,0,1}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1.0cm,y=1.0cm]
\clip(-4.3,-5.28) rectangle (22.8,6.3);
\draw(2.64,1.26) circle (3.73cm);
\draw [color=ttqqqq] (0.28,-1.63)-- (6.26,2.16);
\draw [color=qqttzz] (2.64,1.26)-- (0.28,-1.63);
\draw (2.16,4.96)-- (0.28,-1.63);
\draw [color=qqttzz] (2.64,1.26)-- (2.16,4.96);
\draw [color=qqttzz] (2.64,1.26)-- (6.26,2.16);
\begin{scriptsize}
\fill [color=qqqqff] (2.64,1.26) circle (1.5pt);
\draw[color=qqqqff] (2.78,1.54) node {$A$};
\fill [color=qqqqff] (2.16,4.96) circle (1.5pt);
\draw[color=qqqqff] (2.32,5.24) node {$B$};
\fill [color=xdxdff] (6.26,2.16) circle (1.5pt);
\draw[color=xdxdff] (6.42,2.44) node {$C$};
\fill [color=xdxdff] (0.28,-1.63) circle (1.5pt);
\draw[color=xdxdff] (0.44,-1.34) node {$D$};
\end{scriptsize}
\end{tikzpicture}

\begin{center} 
 $\displaystyle\angle BDC = \frac{1}{2} \widehat{BC} $ 
 \end{center} 

\end{document}

另外，如何为 BA、DA 和 AC 段制作中点标记？

我希望我的绘图看起来像这样，但是带有半径的中点标记：

Answer 1

像这样的基本图形最好直接绘制tikz：

代码：

\documentclass[border=5pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{calc}

\newcommand*{\Radius}{3.0cm}%
\newcommand*{\AAngle}{220}%
\newcommand*{\BAngle}{20}%
\newcommand*{\CAngle}{80}%

\begin{document}
\begin{tikzpicture}[ultra thick, line cap=round,line join=round]
\coordinate (Origin) at (0,0);
\coordinate (A) at (\AAngle:\Radius);
\coordinate (B) at (\BAngle:\Radius);
\coordinate (C) at (\CAngle:\Radius);

\draw [black, thick] (Origin) circle[radius=\Radius];

\draw [brown] 
       (Origin)  node [left, black] {$O$}
    -- (B) node [right, black] {$B$}
    -- (A) node [below left, black] {$A$}
    -- (C) node [above, black] {$C$}
    -- cycle;

\path (Origin) -- (B) node [midway, sloped] {$\mid$};
\path (Origin) -- (C) node [midway, sloped] {$\mid$};

\draw [red] (Origin) ++ (B) arc[radius=\Radius,start angle=\BAngle,end angle=\CAngle];
\end{tikzpicture}
\end{document}

Answer 2

您可以尝试使用 Tikz 的一些基本命令:( 但 Tikz 还有很多其他命令）

\documentclass[10pt]{article}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
 \draw[red] (0,0) (20:3cm)   arc (20:100:3cm);
 \draw[blue] (0,0) (100:3cm) arc (100:380:3cm);
 \fill [color=gray] (20:3cm) circle (1.5pt) node[right,text=black]  {$C$}
        (100:3cm) circle (1.5pt) node[above,text=black]  {$D$};
 \node[red] at (55:3 cm) {//};
\end{tikzpicture}

\end{document}