Take a square paper with side length of 12.56 cm and roll it into a cylinder. The bottom radius of the paper cylinder is 2 cm. What is the bottom area

Take a square paper with side length of 12.56 cm and roll it into a cylinder. The bottom radius of the paper cylinder is 2 cm. What is the bottom area

The bottom area of the cylinder is 3.14 × 2 & # 178; = 12.56 square centimeter
A: the floor area is 12.56 square centimeters

Roll a piece of 18.84 cm, 12.56 cm wide paper into a cylinder, and the bottom area of the cylinder may be () flat
Roll a piece of 18.84 cm, 12.56 cm wide paper into a cylinder. The maximum area of the cylinder is () square cm

18.84 / 3.14 = 6cm
6 / 2 = 3cm
3.14 * 3 * 3 = 28.26 square centimeter

A cylinder, if it is cut into two small cylinders, the surface area increases by 12.56 square centimeters, if it is cut into two and a half cylinders along the diameter of the bottom... Bottom
(for a cylinder, if you cut it into two small cylinders, the surface area will increase by 12.56 square centimeter. If you cut it into two and a half cylinders along the bottom diameter, the surface area will increase by 40 square centimeter. Find the surface area of the cylinder.) to calculate the formula, you'd better not use the equation. If you can't do it, you can only use the equation of one variable once, and you haven't learned other equations! Give a reply within 10 minutes!

If you cut it into two small cylinders, the surface area increases by 12.56 square centimeters, and two bottom surfaces are added, so one bottom surface is 12.56 / 2 = 6.28 square centimeters,
So its radius is one centimeter. Its diameter is two centimeters,
If you cut two and a half cylinders along the bottom diameter, the surface area will increase by 40, and you can know the height: 40 / 2 = 20 cm,
Its surface area is: 3.14 * 2 * 20 + 3.14 * 1 * 1 * 2 = 131.88 square centimeter