## Geometry: Common Core (15th Edition)

Vertex $O$ is at $(0, 0)$. Vertex $S$ has coordinates $(0, a)$. Vertex $W$ has coordinates $(a, 0)$. Vertex $T$ has coordinates $(a, a)$.
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 $(a, a)$.