The answers have square roots among the choices so we probably shouldn't use that calculator button.
We can't just apply the area of the trapezoid formula
[tex]A = \frac 1 2(b + t) h[/tex]
where b is the bottom base, t the parallel top, and h the height, because we don't know the top t.
It will be 10 less the leg of that right triangle, which we calculate as
[tex]l = \sqrt{8^2 - (4\sqrt{3})^2} = \sqrt{64 - 48} = \sqrt{16}=4[/tex]
Now we can apply the trapezoid formula. We have
[tex]b = 10, \qquad t=10-4=6, \qquad h= 4\sqrt{3}[/tex]
[tex]A = \frac 1 2(b + t) h = \frac 1 2 (10 +6)(4 \sqrt{3}) = 32 \sqrt{3}[/tex]
Choice b
