check the picture below.
notice, is just a 6x6 square, therefore its diagonals will cut each other in half, thus they both will meet at their midpoint, so let's check the midpoint for AC then,
[tex]\bf ~~~~~~~~~~~~\textit{middle point of 2 points }\\ \quad \\
\begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&A&(~{{ -2}} &,&{{ 4}}~)
% (c,d)
&C&(~{{ 4}} &,&{{ -2}}~)
\end{array}\qquad
% coordinates of midpoint
\left(\cfrac{{{ x_2}} + {{ x_1}}}{2}\quad ,\quad \cfrac{{{ y_2}} + {{ y_1}}}{2} \right)
\\\\\\
\left( \cfrac{4-2}{2}~~,~~\cfrac{-2+4}{2} \right)\implies \left( \cfrac{2}{2}~~,~~\cfrac{2}{2} \right)\implies (1,1)[/tex]
