AMC 12 2002a Problem 23

In triangle $ABC$, side $AC$ and the perpendicular bisector of $BC$ meet in point $D$, and $BD$ bisects $\angle ABC$. If $AD = 9$ and $DC = 7$, what is the area of triangle $ABD$?

$\text{(A)}\ 14 \text{(B)}\ 21 \text{(C)}\ 28 \text{(D)}\ 14\sqrt5 \text{(E)}\ 28\sqrt5$