答案1
使用极坐标的一种可能性:
\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\usetikzlibrary{arrows}
\begin{document}
\begin{tikzpicture}
\draw (0,0) circle (3cm);
\foreach \mangle/\value in {0/{$0,1$},30/$\dfrac{1}{12}$,45/$\dfrac{1}{8}$,60/$\dfrac{1}{6}$,90/$\dfrac{1}{4}$,120/$\dfrac{1}{3}$,180/$\dfrac{1}{2}$,270/$\dfrac{3}{4}$}
{
\draw (0,0) -- (\mangle:3.5cm);
\node at (\mangle:4) {\value};
}
\begin{scope}[yshift=8cm,>=latex]
\draw (0,0) circle (3cm);
\draw (0,0) circle (1.7cm);
\draw[-] (0,0) -- +(60:3.5cm) ;
\draw[-] (0,0) -- +(30:3.5cm) ;
\draw[->] (0,0) -- node[pos=0.95,left=3pt ] {$r_2$} +(60:3cm) ;
\draw[->] (0,0) -- node[pos=0.6,right=6pt] {$r_1$} +(30:1.7cm) ;
\node at (45:3.3) {$s_2$};
\node at (45:2) {$s_1$};
\node at (45:1) {$\theta$};
\end{scope}
\end{tikzpicture}
\end{document}