1. Points, lines, surfaces and bodies can help people describe the complex world effectively. It's all called geometry. All kinds of figures abstracted from objects are collectively called geometric figures. Geometric figures with parts not in the same plane are called three-dimensional figures. Some geometric figures are all in the same plane, which is called plane figures. Although solid figure and plane figure are two different geometric figures, they are interrelated. Geometric graphics are generally divided into three-dimensional graphics and plane graphics.

2. Concept of geometry: Geometry is abbreviated as body, such as cube, sphere, pyramid, etc. Surrounding the body is a surface, which has two kinds: plane and curved surface. The intersection of faces forms a line, and the intersection of lines is called a point. 3. Understand points, lines, surfaces and bodies from the viewpoint of movement. Points become lines, lines become faces, and faces become bodies.

3. How to classify solid geometric figures?

Can be divided into the following categories: the first category: cylinder; Comprises a cylinder and a prism, wherein the prism can be divided into a straight prism and an oblique prism, and the prism can be divided into a triangular prism, a quadrangular prism and an N prism according to the number of sides of the bottom surface; The unit of volume of a prism is equal to the area of the base multiplied by the height, that is, V=SH, and the second type: cone; Comprises a cone and a pyramid, wherein the pyramid is divided into a triangular pyramid, a quadrangular pyramid and an n-pyramid; The pyramid volume is unified as V=SH/3, and the third category: rotating body: including: cylinder; Round table; Cone; Ball; Spherical crown; Bow ring; Ring; Dike ring; Fan ring; Jujube stone shape; The formula for its surface area is: S=2*L*π*R(L is the perimeter of the base figure, π is a constant, and R is the distance from the center of gravity to the axis), and its volume formula is: V=2*S*π*R(S is the area of the base figure, π is a constant, and R is the distance from the center of gravity to the axis). The fourth category: section body; Comprises a frustum; Round table; Oblique truncated cylinder; Oblique prism; Oblique truncated cone; Spherical crown; Generally speaking, the surface area and volume of spherical defects are solved by adding and subtracting numbers.

4. How to classify plane geometry?

1. circle (including perfect circle and ellipse) 2. Polygon: triangle (divided into general triangle, right triangle, isosceles triangle and equilateral triangle), quadrilateral (divided into irregular quadrilateral, figure, parallelogram and parallelogram divided into rectangle, diamond and square), pentagon and hexagon ... Note: square is both rectangular and diamond. 3. Bow (a figure composed of straight lines and arcs, including upper bow, lower bow, parabolic bow, etc.). ) .4. Multi-arcs (including crescent moon, pattern, Tai Chi gourd, etc.). )