\begin{tikzpicture}[rotate=90]
 \tkzDefPoint[label=right:$A_n$](2,3){A}
 \begin{scope}[shift={(A)}]
  \tkzDefPoint[label= right:$B_n$](31:3){B}
  \tkzDefPoint[label= right:$C_n$](158:3){C}
 \end{scope}
  \tkzDrawSegments[color=red,%
           line width=1pt](A,B A,C)
  \tkzDrawPoints[color=red](A,B,C)
 \end{tikzpicture}
