\begin{tikzpicture}[scale=1] \tkzDefPoint(0,4){A} \tkzDefPoint(2,2){B} \tkzDefMidPoint(A,B) \tkzGetPoint{I} \tkzDefRandPointOn[segment = I--B] \tkzGetPoint{C} \tkzDefCircle[through](A,C) \tkzGetLength{rACpt} \tkzpttocm(\rACpt){rACcm} \tkzDrawCircle(A,C) \tkzDrawPoints(A,B,C) \tkzLabelPoints(A,B,C) \tkzLabelCircle[draw,fill=Gold,% text width=3cm,text centered, font=\scriptsize](A,C)(-90)% {La mesure du rayon est : \rACpt pt soit \rACcm cm} \end{tikzpicture}