Given the areas of the three squares in the figure, what is the area of the interior triangle?

$\mathrm{(A)}\ 13 \qquad\mathrm{(B)}\ 30 \qquad\mathrm{(C)}\ 60 \qquad\mathrm{(D)}\ 300 \qquad\mathrm{(E)}\ 1800$
The sides of the squares are $5, 12$ and $13$ for the square with area $25, 144$ and $169$, respectively. The legs of the interior triangle are $5$ and $12$, so the area is $\frac{5 \times 12}{2}=\boxed{\mathrm{(B)}\ 30}$