答案1
有以下可能性:
\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
\coordinate (c);
\def\firststep{3cm}
\foreach \step in {1,...,5}{
\pgfmathsetmacro\mypow{2^\step}
% Achille
\draw[blue,fill=blue!10] (c) arc(180:0:\firststep/\mypow) coordinate(c);
% Turtle
\draw[red,fill=red!10] (c) arc(-180:0:\firststep/\mypow/2);
}
\draw[green] (0,0) -- (\firststep * 2, 0);
\end{tikzpicture}
\end{document}