[填空题]
The following diagram shows a circle w h r2f9ernyf0;h,z:qfith centre O and radius 5 cmwfp4.5ubc.g2( f 8.is kgcqg a.
Points $ \mathrm{A}$,$ \mathrm{B} $ lie on the circle and $ \mathrm{AO} \mathrm{B}=2.1 $ radians.
1. Find the length of:
1. minor arc A B ; cm
2. chord A B .≈ cm
2. Find the area of the shaded region.≈ $cm ^2$
