1)   Let  A, B, C, and D  be vertices of a rectangle with length a units and height units.

2)   Place the rectangle with vertex A at the origin, along the positive x-axis,

       and along the y-axis. Label the vertices A, B, C, and D.

3)   The y-coordinate of B is 0 because the vertex is on the x-axis.

       Since the side length is a, the x-coordinate is a.

4)   The vertex D is on the y-axis so the x-coordinate is 0.

       Since the height is units, y-coordinate is .

5)  The x-coordinate of C is also a.

      Since the side is units long, the y-coordinate of C is .

The ractangle with length a units and height  units is