Answer
Vertex $O$ is at $(0, 0)$.
Vertex $S$ has coordinates $(0, a)$.
Vertex $W$ has coordinates $(a, 0)$.
Vertex $T$ has coordinates $(a, a)$.
Work Step by Step
A square would have sides of equal lengths; in this case, our square has sides of length $a$ each.
Vertex $O$ is at the origin at $(0, 0)$.
Vertex $S$ has no $x$ value, but the $y$ value is equal to the length $a$. Therefore, vertex $S$ has coordinates $(0, a)$.
Vertex $W$ has an $x$ value equal to the length $a$, but there is no $y$ value. Therefore, vertex $W$ has coordinates $(a, 0)$.
Vertex $T$ has an $x$ value equal to the length $a$ and a $y$ value equal to the length $a$ as well. Therefore, vertex $T$ has coordinates $(a, a)$.
