\begin{tikzpicture} \tikzstyle{point}=[thick,draw=black,cross out,inner sep=0pt,minimum width=4pt,minimum height=4pt] \begin{axis}[ legend pos=south west, axis x line=middle, axis y line=middle, grid = major, width=5cm, height=5cm, grid style={dashed, gray!30}, xmin=0, % start the diagram at this x-coordinate xmax=3, % end the diagram at this x-coordinate ymin=0, % start the diagram at this y-coordinate ymax=3, % end the diagram at this y-coordinate tick align=outside, minor tick num=-3, enlargelimits=true, tension=0.08] \node (a)[point,label={[label distance=0cm]5:$e_0$}] at (axis cs:2.5,0) {}; \node (b)[point,label={[label distance=0cm]5:$e_1$}] at (axis cs:0,2.5) {}; \node (c)[point,label={[label distance=0cm]0:$e_2$}] at (axis cs:2,2) {}; \draw[thick,fill=orange!50] (a.center) -- (b.center) -- (c.center) -- cycle; \end{axis} \end{tikzpicture}