1. Cut out the largest circle in a square with a side length of 4 cm. The area of the circle is (12.56) square cm 2. The diameter of the outer circle is 8 decimeters, the radius of the inner circle is 2 decimeters, and the area of this circle is () square decimeters 3. The radius of a semicircle is 6 decimeters, and its circumference is (37.68) decimeters 4. A circle with a circumference of 28.26 meters, if its diameter expands to three times of the original, its area expands to () times

1. Cut out the largest circle in a square with a side length of 4 cm. The area of the circle is (12.56) square cm 2. The diameter of the outer circle is 8 decimeters, the radius of the inner circle is 2 decimeters, and the area of this circle is () square decimeters 3. The radius of a semicircle is 6 decimeters, and its circumference is (37.68) decimeters 4. A circle with a circumference of 28.26 meters, if its diameter expands to three times of the original, its area expands to () times

1.12.56
2.37.68
3.18.84
9 times