documentclass{standalone}
usepackage{tikz}
usetikzlibrary{positioning,shapes}
begin{document}
begin{tikzpicture}[border rotated/.style = {shape border rotate=180},triangle/.style={draw, shape=regular polygon, regular polygon
sides=3,draw,thick,inner sep=0pt,minimum size=2cm,inner sep=0pt,outer
sep=0pt}]
node [triangle,fill=yellow!15](1) {};
node [triangle,fill=red!25,border rotated,right=0pt of 1](2)  {};
node [triangle,fill=blue!15,right=0pt of 2](3) {};
end{tikzpicture}
end{document}