#### Answer

$A: 0,0 \\ B: 0,a \\ C: a,a \\ D: a,0$

#### Work Step by Step

We call the point A at the origin, which is $(0,0)$. We call the length of a side of square ABCD length a. Thus, we obtain the lengths of the other sides using this information:
$A: 0,0 \\ B: 0,a \\ C: a,a \\ D: a,0$