1. Given functions
$$
f(x)=\sin x, g(x)=\sqrt{\pi^{2}-x^{2}}
$$

have the domain $[-\pi, \pi]$. The area of the region enclosed by their graphs is . $\qquad$
$$
\text { II. } 1 \cdot \frac{\pi^{3}}{2} \text {. }
$$

To complete the graph of $y=\sqrt{\pi^{2}-x^{2}}$ into a full circle, by central symmetry, it is easy to see that the desired area is half of the circle's area.