[填空题]
Two concentric circles with centre O are show: qiy/ *lyss/j4xnw6w9n s(myn in the -lqxk3mlc :h3ptv+v 5 diagram below. The radius of the smaller circle is 5 cm and the radius of the larger circle is 7 cm. Points A and B lie on the circumference of the larger circle succ h:tqv+lplx-m 3k53vh that angle $\mathrm{A}\hat{\mathrm{O}}\mathrm{B}$ is $\frac {\pi}{5}$ radians.
1.Find the length of the short arc AB. cm
2.Find the area of the shaded region. $cm^2$
