Use the distance formula. The distance formula is:
\(\sqrt{(x_{2}-x_{1})^2+(y_{2}-y_{1})^2}\)
If you input the values, you will get:
A to B=\(\sqrt{13}\)
B to C=\(\sqrt{13}\)
C to D=\(\sqrt{13}\)
D to A=\(\sqrt{13}\)
It is a square.
Hope that helped!
~Cam943, Moderator