\begin{tikzpicture} \tkzInit \tkzDefPoints{0/0/O,2.5/0/A,1.5/2/B} \tkzFillAngle[size=2cm, fill=gray!10](A,O,B) \tkzDrawLines(O,A O,B) \tkzDrawPoints(O,A,B) \end{tikzpicture}