For a 10 cm high steel cylinder, the surface area will be reduced by 18.84 square centimeters if the 2 cm high steel cylinder is cut first Fast, fast, fast, fast

For a 10 cm high steel cylinder, the surface area will be reduced by 18.84 square centimeters if the 2 cm high steel cylinder is cut first Fast, fast, fast, fast

The reduced surface area is the side area of the small cylinder
Then radius = 18.84 / (2 * 3.14 * 2) = 1.5cm
Then the volume of the original cylindrical steel = 3.14 * 1.5 * 1.5 * 10 = 70.55 cubic centimeter

How to calculate the surface area of the cylinder? The gods help
Base area plus side area of a cylinder

Cylinder surface area = side area + 2 × bottom area? Side area = bottom perimeter × height? Bottom area = circumference × bottom radius? Cylinder surface area = 2 × circumference × bottom radius × (bottom radius + height)

Cuboid and cube volume problems
1. A square iron block with an edge length of 14 cm is cast into a cuboid iron block with a bottom area of 112 square cm. How high is the cuboid iron block?
2. After sawing a 2-meter-long timber into six identical sections, the surface area of the timber increases by 135 square centimeters. What is the original volume of the timber?

(1) 14 ^ 3 △ 112 = 24.5cm
(2) Cut into six sections, that is, cut five times, and each time add two bottom areas. So a total of 2 × 5 = 10 bottom areas are added, and these 10 bottom areas are 135 square centimeters
200 × (135 △ 10) = 2700 CC
Don't copy mine on the first floor. I've changed it. I won't go along with you. Wahaha!