[填空题]
Two concentric circles with centre O are dk7j ua+rd )36 ia.eryshown *pa dvtx)8zp1 in the diagram below. The radius of the smaller circle is 5 cm and the radius of tax)t 8*1z ppdvhe larger circle is 7 cm. Points A and B lie on the circumference of the larger circle such 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. $cm^2$
