the distances of WX and ZY have to be the same length, since is a parallelogram, and also the distances of WZ and XY.... well, the WX and ZY you can pretty much pick them out from the grid, just count the units
now, to get WZ and XY
[tex]\bf \textit{distance between 2 points}\\ \quad \\
\begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
X&({{2 }}\quad ,&{{ 4}})\quad
% (c,d)
Y&({{1}}\quad ,&{{ -1}})
\end{array}\qquad
% distance value
d = \sqrt{({{ x_2}}-{{ x_1}})^2 + ({{ y_2}}-{{ y_1}})^2}
\\\\\\
\overline{XY}=\sqrt{(1-2)^2+(-1-4)^2}[/tex]
whatever that gives you, is the same length for WZ, and then just add all 4 segments up, that's the perimeter of the figure
