\documentclass[12pt,a4paper]{standalone}
\usepackage{tikz,tkz-euclide,pgfplots}
\usetkzobj{all}
\begin{document}%
\begin{tikzpicture}
\tkzInit[ymax=4.5, xmax=6.5,xmin=-1.5,ymin=-0.5]
\tkzAxeXY
\tkzDefPoint(1,1){A}
\tkzDefPoint(5,2){B}
\tkzDefPoint(3,4){C}
\tkzDefPoint(0,0){O}
\tkzDefMidPoint(A,B) \tkzGetPoint{M1}
\tkzDefMidPoint(B,C) \tkzGetPoint{M2}
\tkzDefMidPoint(A,C) \tkzGetPoint{M3}
\tkzInterLL(A,M2)(C,M1) \tkzGetPoint{T}
\tkzDrawSegments[dashed,thick](A,M2 C,M1 B,M3)
\tkzDrawPolygon[color=blue,thick](A,B,C)