[填空题]
The following diagram so i3-gn4uggn3 hows a cqhx :rwtz2xmw :k6 48*tg )xrkircle with centre O and radius 5 cm.
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.≈ $cm ^2$
