Cut a cube with an edge length of 8 cm into the largest cylinder with a surface area of () square cm and a volume of () cubic cm

Cut a cube with an edge length of 8 cm into the largest cylinder with a surface area of () square cm and a volume of () cubic cm

Surface area: 3.14 × 8 × 8 + 3.14 × (8 / 2) &# 178; × 2 = 301.44 square centimeter
Volume: 3.14 × (8 / 2) &# 178; × 8 = 401.92 cm3

The surface area of a cylinder is 210 square decimeters, and the bottom radius is 40% of the height. What is the bottom area of the cylinder
Have symbols that you can understand, quick

Radius = height × 40%
So: height = 2.5 radius
Surface area
=2 × bottom area + side area
=2 × π × radius & # 178; + 2 × radius × π × 2.5 radius
=7 π radius & # 178;
So:
7 π radius & # 178; = 210
π × radius & # 178; = 210 △ 7 = 30 square decimeters
That is: bottom area = 30 square decimeters

Roll a rectangle 12 decimeters long and 5 decimeters wide into the largest cylindrical paper tube. The side area of this paper tube is (). There are 50 gold coins,
2. Cut a cube with 12cm edge length into the largest cone. The volume of the cone is ()

Cut into the largest cone, then the bottom of the cone is in the bottom of the cube
So the bottom side length of the cube 12 is the diameter of the cone bottom circle
The height of the cube 12 is the height of the cone
Because the conic volume formula is:
V＝1/3Sh（V＝1/3SH）
V=1/3 π r2 h=1/3π6*6*12=452.16