What is the meaning of cylinder?

• 圆

• 圆锥

• 圆柱

• 三角形

5.4 dm³=（ ）cm³

The total surface area of a cylinder with a radius of 3 dm and a height of 5 dm is __________ dm^2.

The volume of a cylinder with a height of 5 cm and a base radius of 3 cm is __________ cm³.

The height of a cone with a volume of 24 m³ and a base area of 12 m² is ________ m.

If the height of a cone is fixed and its base area is tripled, then its volume will be _____

• enlarged nine time as large as its original volume.

• tripled

• unchanged

• doubled

solve the proportion
 $\frac{x}{x+0.4}=\frac{3}{4}$  

What is the reading? Don't type the unit.

Solve the proportion $\frac{x}{x+1.3}=\frac{2}{3}$  

Please find the correct statement(s).

• For a cylinder, the net of its lateral surface will never be a parallelogram.

• •The volume of a cone is one third of the volume of a cylinder.

• •If the height of a cylinder is doubled and its base area is halved, then its volume does not change.

• •If the lateral surface areas of two cylinders are the same, then their volumes are equal.

• •A cylinder has countless heights while a cone has one and only one height.