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Five sixth grade math problems, help It's all about cylinders 1. Diameter = 8 cm, height = 4 cm, find the surface area of the cylinder 2. Radius = 5cm, height = 25cm, find the surface area of the cylinder 3. Perimeter = 62.8 cm, height = 4 cm, find the surface area of the cylinder 4. The side view of a cylinder is square, and the diameter of its bottom is 6cm 5. The side area of a cylinder is 251.2 square centimeters, and the height is 10 centimeters. What is the radius of its bottom? What is the bottom area? Brothers and sisters, aunts and aunts, aunts and uncles, help me!
1 ` the radius of the bottom surface is calculated first
8/2=4CM
4 * 4 * 3.14 * 2 = 100.48 square centimeter (area of upper and lower circles)
8 * 3.14 = 25.12cm (bottom perimeter)
25.12 * 4 = 100.48 square centimeter (side area)
100.48 = 100.48 = 200.96 square centimeter
2`
5*5*3.14*2+5*2*3.14*25=942
3`
62.8 / 3.14 / 2 = 10 cm (bottom radius)
10 * 10 * 3.14 * 2 = 628 square centimeters (bottom area)
62.8 * 4 = 251.2 square centimeter (side area)
251.2 + 628 = 879.2 square centimeter
4`
6 * 3.14 = 18.84cm
5`
251.2/10 = 25.12 cm (bottom perimeter)
25.12/3.14/2 = 4cm (bottom radius)
3.14 * 4 * 4 = 50.24 square centimeter (bottom area)
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