% 6-4-3.ty
\documentclass{article}
\input tdw
\begin{document}
\setlength{\unitlength}{1mm}
\begin{center}
\begin{picture}(44,44)(-20,-20)
\put(0,0){\draw0,0,{width(.4),
circle(0,0,20),
threed(20.7,70.3),
trace(-69.3*pi/180,110.7*pi/180,20cos(t),20sin(t),0),
trace(-0.366,pi-0.366,20sin(t),0,20cos(t)),
trace(-0.792,pi-0.792,0,20sin(t),20cos(t)),
line(20,0,0,28,0,0),
line(0,20,0,0,24,0),
line(0,0,20,0,0,24),
arrowheadd(28,0,0,1,0,0,2,10),
arrowheadd(0,24,0,0,1,0,2,10),
arrowheadd(0,0,24,0,0,1,2,10),
write(29,0,0)[rt]{$x$},
write(0,25,0)[l]{$y$},
write(0,0,25)[b]{$z$},
write(0,0,-0.5)[lt]{$O$},
dotted(6,7),width(.2),
trace(110.7*pi/180,290.7*pi/180,20cos(t),20sin(t),0),
trace(2pi-0.366,pi-0.366,20sin(t),0,20cos(t)),
trace(2pi-0.792,pi-0.792,0,20sin(t),20cos(t)),
line(-20,0,0,20,0,0),
line(0,-20,0,0,20,0),
line(0,0,-20,0,0,20)}}
\end{picture}
\qquad
\begin{picture}(44,44)(-20,-20)
\put(0,0){\draw0,0,{width(.4),
circle(0,0,20),
threed(45,45),
trace(-69.3*pi/180,110.7*pi/180,20cos(t),20sin(t),0),
trace(-0.366,pi-0.366,20sin(t),0,20cos(t)),
trace(-0.792,pi-0.792,0,20sin(t),20cos(t)),
line(20,0,0,28,0,0),
line(0,20,0,0,24,0),
line(0,0,20,0,0,24),
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arrowheadd(0,24,0,0,1,0,2,10),
arrowheadd(0,0,24,0,0,1,2,10),
write(29,0,0)[rt]{$x$},
write(0,25,0)[l]{$y$},
write(0,0,25)[b]{$z$},
write(0,0,-0.5)[lt]{$O$},
dotted(6,7),width(.2),
trace(110.7*pi/180,290.7*pi/180,20cos(t),20sin(t),0),
trace(2pi-0.366,pi-0.366,20sin(t),0,20cos(t)),
trace(2pi-0.792,pi-0.792,0,20sin(t),20cos(t)),
line(-20,0,0,20,0,0),
line(0,-20,0,0,20,0),
line(0,0,-20,0,0,20)}}
\end{picture}
\end{center}
\end{document}