Build a cylindrical biogas digester. The perimeter of the bottom surface is 18.84 meters and the depth is 2 meters. Cement the four walls and the bottom surface of the digester. How many square meters is the area of the cement part?

Build a cylindrical biogas digester. The perimeter of the bottom surface is 18.84 meters and the depth is 2 meters. Cement the four walls and the bottom surface of the digester. How many square meters is the area of the cement part?

Side area of biogas digester: 18.84 × 2 = 37.68 (square meters) bottom radius: 18.84 △ 3.14 △ 2 = 3 (meters) bottom area of biogas digester: 3.14 × 32 = 3.14 × 9 = 28.26 (square meters) area of cement plastering part: 37.68 + 28.26 = 65.94 (square meters) a: area of cement plastering part is 65.94 square meters

There is a column in a certain place, the thickest diameter is 1.2, what is the volume of the column? Paint the column, what is the area of the paint

Radius = 1.2 / 2 = 0.6
Volume = 3.14 * 0.6 * 0.6 * 12 = 13.5648 ≈ 13.6
Area = 3.14 * 1.2 * 12 = 45.216 = ≈ 45.2

There are three 4-meter-high pillars in the corridor on the first floor of the teaching building. The bottom surface of each pillar is a square with a side length of 50 cm. Now, how many kg of paint does it need to paint these three pillars? (about 0.5 kg of paint per square meter

3 * 4 * 0.5 * 0.5 * 4 = 12kg