1, the perimeter of the bottom is the length of the rectangular iron sheet: 2X3. 14X(2/2)=6.28 (decimeter). The height of the cylinder is the width of the iron sheet. A: The rectangular iron sheet is 6.28 decimeters long and 3 decimeters wide. 2. two kinds. One uses a 5 cm edge as the bottom of the cylinder, and the height at this time is 4 cm. One has a side of 4 cm as the bottom of the cylinder, and the height is 5 cm at this time. 3. Bottom circumference of seeder drum: 2x3.14x (1/2) = 3.14 (m) Cylindrical area of seeder drum: 3.14x1= 3. Surface area increase: 3. 1 4x (square of 20) X6=7536 (square centimeter) 5,1liter = 1 cubic decimeter The height of water in the bucket is: (40/6)X(3/4)=5 (decimeter) Application problems. 2 = 2=3 (cm) =0.03 half an hour = per second 1800s: 3.14x (0.03m2) X4 half an hour: 3.14x (0.03m2) x4x1800 = 20. =6.28 (m) Cylinder area of front wheel: 6.28X 1.5=9.42 (m2). The number of meters in half an hour is: 6.28X 15X30=2826 (meters). The road area for working for one hour is 9.42 x 15x60 = 80. The diameter and height of the cylinder bottom are: root number 36=6 (cm), the circumference of the cylinder bottom with a radius of 3cm is 2x3.14x3 =18.84 (cm), and the area of the cylinder bottom is 3.14x (the square of 3) =28.26 (cm 2).