\input{preamble-standalone.ltx} \begin{document} % Ex. No. 150 (Section 19.1.1 : Circles and styles, draw a circle and color the disc) \begin{tikzpicture} \tkzDefPoint(0,0){O} \tkzDefPoint(3,0){A} \tkzDrawCircle[color=blue](O,A) \tkzDrawCircle[diameter,color=red,% line width=2pt,fill=red!40,% opacity=.5](O,A) \edef\rayon{\fpeval{0.25*exp(1)}} \tkzDrawCircle[R,color=orange](O,\rayon cm) \end{tikzpicture} \end{document}