All sides of the [convex](https://artofproblemsolving.com/wiki/index.php/Convex_polygon) [pentagon](https://artofproblemsolving.com/wiki/index.php/Pentagon) $ABCDE$ are of equal length, and $\angle A = \angle B = 90^{\circ}$. What is the degree measure of $\angle E$? 
$\mathrm {(A)}\ 90 \qquad \mathrm {(B)}\ 108 \qquad \mathrm {(C)}\ 120 \qquad \mathrm {(D)}\ 144 \qquad \mathrm {(E)}\ 150$
[2007 12B AMC-7.png](https://artofproblemsolving.com/wiki/index.php/File:2007_12B_AMC-7.png)
Since $A$ and $B$ are [right angles](https://artofproblemsolving.com/wiki/index.php/Right_angle), and $AE$ equals $BC$, and $AECB$ is a [square](https://artofproblemsolving.com/wiki/index.php/Square). Since $ED$ and $CD$ are also 5, triangle $CDE$ is [equilateral](https://artofproblemsolving.com/wiki/index.php/Equilateral_triangle). Angle $E$ is therefore $90+60=150 \Rightarrow \mathrm {(E)}$