24. An isosceles trapezoid is circumscribed around a circle, with the longer base being 16, and one of the base angles being $\arcsin 0.8$. The area of the trapezoid is 
(A) 72. (B) 75. (C) 80. (D) 90.
(E) Not uniquely determined.
24
24. The non-parallel sides of an isosceles trapezoid are tangents to a circle, and the sum of the two bases equals the sum of the two non-parallel sides. As shown in the figure, let $x, y$, then
$$
\left\{\begin{array}{l}
2 y+1.2 x=2 x \\
y+1.2 x=16
\end{array}\right.
$$

Solving it, we get $x=10, y=4$.
$\therefore S=\frac{1}{2}(4+16) \cdot 8=80$. Therefore, the correct choice is (C).