[填空题]
During a hiking trip, pqu0y(f5iq41b6qwv6x e epi8 4l+l 6.dcz wx.6 yr6ayp az0knJim stopped and checked his compass for directions. The compass has a circular face with centre at O and the diameter of 20 cm. The needle of the compass is at ank6pdl0yzw66 .y.z+r aca4l x n angle of $\theta$ to the East of North, covering an arc length of $l$, as illustrated in the diagram below.
1.Determine the circumference of the face of the compass. cm
2.Using the diagram, write down the size of the angle $\theta$ in degrees. $^{\circ}$
3.Calculate the arc length, $l$. cm
4.Calculate the total area of the shaded sectors on the diagram. $cm^2$
