2. The diameter of a circle is 6 cm, so its area is __28.26__ square cm?
3. The circumference of a circle is 6.28cm, so its area is _ 3. 14 _ _ cm2?
4. The central angle of the sector is 150 degrees, the radius is 3cm, and the area is _1.775 _ _ cm2?
5. The arc length of the sector is 12.56cm and the radius is 5cm. Its area is _ _ 3 1.4 _ _ cm2?
6. If the radius of a circle is enlarged by 1 times, the area of the circle will be enlarged by _3____ times?
7. If the circumference of a circle is expanded to 4 times, the area of the circle will be expanded to __ 16__?
8. The area of a sector is 7.065 square centimeters, and the radius of this sector is 3 centimeters. So the central angle of this sector is _90__?
9. The area of the sector is 5/8 of the circular area, and the central angle of the sector is __225__?
10. The radius of circle A is 3/5 of the radius of circle B, so the area of circle A is __9/25__ of circle B?
1 1. The circumference of circle A is 7/9 of the length of circle B, so the area of circle A is _49/8 1__?
12. If the diameter of the outer circle of the ring is 6 cm and the diameter of the inner circle is 4 cm, the area of the ring is _ 15.7__?
13. If the area of a sector with a central angle of 60 degrees is 3 14cm2, then the area of the circle where this sector is located is _ 1884 _ _ cm2?
14. Cut out the largest circle in a rectangle with a length of 10 cm and a length of 8 cm. The area of this circle is _50.24_?