AHSME 1980 Problem 7

Sides $AB,BC,CD$ and $DA$ of convex polygon $ABCD$ have lengths 3, 4, 12, and 13, respectively, and $\angle CBA$ is a right angle. The area of the quadrilateral is

$\text{(A)} \ 32 \text{(B)} \ 36 \text{(C)} \ 39 \text{(D)} \ 42 \text{(E)} \ 48$