[填空题]
The diagram below showckz wjn ;kgzs ,4fk05;s (z q 58gpsn:rca circle of radius 9 cm. The points A, B, C and D lie on the circlr8 qs(:zp5nc ge.
1. Find A C . ≈
2. 1. Find DĈA.≈
2. Hence find A C $\hat{B}$ .≈
3. Find the area of triangle A C D .≈
4. Hence, or otherwise, find the total area of the shaded region.