Answer
32
Work Step by Step
We first cut the base into half by creating a diagonal of length 5 from the upper right hand corner. Next, knowing that the distance between this diagonal and the altitude that starts at the upper right hand corner is 3, we find:
$h = \sqrt{5^2 - 3^2} = 4 $
Using this, we find:
$ A = 1/2(b_1 + b_2)(h) = 1/2(16)(4)=32$
