A square of area 40 is inscribed in a semicircle as shown. What is the area of the semicircle? [asy]
defaultpen(linewidth(0.8));
real r=sqrt(50), s=sqrt(10);
draw(Arc(origin, r, 0, 180));
draw((r,0)--(-r,0), dashed);
draw((s,0)--(s,2*s)--(-s,2*s)--(-s,0));[/asy]<spanclass=′latex−bold′>(A)</span>20π<spanclass=′latex−bold′>(B)</span>25π<spanclass=′latex−bold′>(C)</span>30π<spanclass=′latex−bold′>(D)</span>40π<spanclass=′latex−bold′>(E)</span>50π