There is a cylindrical pile, cut along the diameter, the section is a square, the circumference of the bottom of the cylinder is 12.56 decimeters, circle

Find the area of a circle? 12.56 △ 3.14 △ 2 = 2 (decimeter) 3.14 × 2 × 2 = 12.56 (square decimeter)

RELATED INFORMATIONS

1. A cylinder with a height of 6.28 decimeters, its side area expansion is just a square, how many square decimeters is its surface area? Make it clear,
2. There are two ways to encircle a cylinder with a rectangular sheet of iron 31.4 decimeters long and 12.56 decimeters wide. One is () decimeters in diameter and () decimeters in height. The other is () decimeters in diameter and () decimeters in height
3. The volume of a cone is 6 cubic decimeters less than that of a cylinder. What is the volume of a cone and that of a cylinder
4. The volume difference between a cylinder with equal base and height and a cone is 9.42 cubic centimeter. What is the volume of cone? What is the volume of cylinder?
5. What is the volume ratio of a cylinder with equal base and height to a cone? How many percent more is the volume of a cylinder than that of a cone? What is the volume ratio of a cone to that of a cylinder What's the volume?
6. The volume of a cylinder with equal base and height is larger than that of a cone______ %The volume of a cone is less than that of a cylinder
7. The volume of the cone is 15 cubic decimeters, the bottom area is 10 square decimeters, and the height of the cone is 15 cubic meters______ Decimeter
8. It is known that the volume of a cone is 12 cubic decimeters less than that of a cylinder______ Cubic decimeter
9. If the side area of the cylinder is 37.68 square decimeters and the height is three decimeters, its volume is () cubic decimeters
10. How much will the surface area increase when a cylinder with a bottom diameter of 2 decimeters and a height of 5 decimeters is sawed into two cylinders of exactly the same size?
11. The side of a cylinder is a square. The perimeter of the square is 6.28 decimeters. What is the volume of the cylinder? Help me
12. The lobby of a hotel has 6 large cylindrical columns, 10 meters high and 25.12 decimeters in circumference. All the columns should be painted. If the painting fee per square meter is 80 yuan, how much will it cost?
13. The diameter of the bottom of the pillars in the hall is 6 decimeters, and the height is 5 meters. Paint the eight pillars. Use 0.5 kg per square meter. How much paint do you need?
14. There are two cuboid pillars in the children's palace, 4 meters high, with a square bottom and a circumference of 1.2 meters, What is the total area of the two pillars painted? It's a formula!
15. There are 10 columns in the corridor. The radius of the bottom of each column is 4 decimeters and the height is 2.5 meters There are 10 cylindrical columns in the school corridor. The bottom radius of each column is 4 decimeters, and the height is 2.5 meters. To paint these columns for the celebration of June 1 performance, 0.3 kg of paint is used per square meter. How many kg of paint are needed?
16. There are four cylindrical columns in the corridor outside the classroom. The diameter of the bottom of each column is 6 decimeters. Paint these columns with 0.3 paint per square meter Kg, how many kg of paint are needed? (the number obtained shall be kept to two decimal places)
17. There are four cuboid columns in the school auditorium, with a square bottom, a side length of 0.6 meters and a height of 5 meters. Paint the four sides of the column Please mark whether you are sure after answering,
18. There are four cuboid pillars in the auditorium. The bottom is a square with a side length of 5 decimeters and a height of 5 meters. What is the area of painting these pillars/
19. There are four cuboid shaped pillars in the auditorium. The bottom is square, with a side length of 6 decimeters and a height of 5 meters. If you want to paint the four pillars, how many square meters is the paint area?
20. There are 10 cylindrical columns in the school corridor. The diameter of the bottom of each column is 4 decimeters and the height is 2.5 meters. To paint these columns, 0.3 kg of paint is used per square meter. How many kg of paint is needed? There is a process