Plot the points $A=(2,0)$, $B=(6,0)$, $C=(5,4)$, and $D=(3,4)$ on a coordinate plane on a piece of paper. Draw the segments $\overline{AB}$, $\overline{BC}$, $\overline{CD}$ and $\overline{DA}$.

The quadrilateral $ABCD$ is commonly called a .
Its area equals .