1, features: all six faces are rectangles (sometimes two opposite faces are squares).

The areas of the opposite sides are equal, and the lengths of the four opposite sides of 12 are equal. There are eight vertices. The lengths of three sides intersecting at a vertex are called length, width and height respectively. An edge where two faces intersect is called an edge.

The point where three sides intersect is called a vertex.

If you put a cuboid on the desktop, you can only see three faces at most.

The total area of six faces of a cuboid or cube is called its surface area.

2. Calculation formula

s=2(ab+ah+bh) V=sh V=abh

(2) Cube

1, features: all six faces are squares.

The area of six faces is equal to 12 sides, and the lengths of the sides are all equal, with 8 vertices.

A cube can be regarded as a special cuboid.

2, calculation formula s table =6a

v=a

(3) Cylinder

1, the understanding of the cylinder The upper and lower surfaces of the cylinder are called the bottom surface.

A cylinder has a surface called a side. The distance between the two bottom surfaces of a cylinder is called the height.

One-step method: more materials are actually used than the calculated results.

So when you want to keep the number, if the omitted number is 4 or less, you must go forward 1. This approximate method is called step-by-step method.

2. Calculate formula S side =ch.

S table =s side +s bottom ×2

v=sh/3

(4) Cone

Understanding of cone

The bottom of the cone is a circle, and the side of the cone is a surface.

The distance from the apex of the cone to the center of the bottom surface is the height of the cone.

Measuring the height of the cone: firstly, lay the bottom of the cone flat, place a flat plate horizontally above the apex of the cone, and measure the distance between the flat plate and the bottom vertically.

Enlarge the side of the cone to get a sector.

2 calculation formula v= sh/3

(5) Ball

1, understand

The surface of a sphere is a curved surface, called a sphere.

Like a circle, the ball also has a center, which is represented by O.

The line segment from the center of the sphere to any point on the sphere is called the spherical radius, which is denoted by R, and each radius is equal.

The line segment passing through the center of the sphere with both ends on the sphere is called the diameter of the sphere, which is denoted by d, and the diameters are equal.

The length of the diameter is equal to twice the radius, that is, d=2r.

2 calculation formula d=2r