需要通过验证才能下载！希望大家多多合作！否则不能下载！请谅解！

				% 6-4-2.ty
				\documentclass{article}
				\input tdw
				\begin{document}
				\setlength{\unitlength}{1mm}
				\begin{center}
				\begin{picture}(70,28)(-3,-3)\small
				\put(-3,0){\vector(1,0){70}}
				\put(0,-3){\vector(0,1){28}}
				\put(0,0){\draw0,0,{width(0.4),
				trace(0.01,2pi-0.01,10(t-sin(t)),10(1-cos(t))),
				width(0.2),
				circle(15.7,10,10),
				polygon(5.7,10,15.7,10,15.7,0),
				trace(pi,1.5pi,15.7+3cos(t),10+3sin(t)),
				write(-0.5,-0.5)[rt]{$O$},
				write(20pi,-1)[t]{$A$},
				write(12.7,8)[rt]{$\theta$}}}
				\end{picture}
				\end{center}
				\end{document}