\begin{tikzpicture}[rotate=-45,scale=.75]
  \tkzDefPoint(2,1){A}
     \tkzDefPoint(6,5){B}
  \tkzDefPoint(3,6){C}
     \tkzDefPoint(5,2){D}
  \tkzDrawLines(A,B C,D)
  \tkzInterLL(A,B)(C,D)
     \tkzGetPoint{I}
  \tkzDrawPoints[color=blue](A,B,C,D)
   \tkzDrawPoint[color=red](I)
\end{tikzpicture}
