What do you mean by cross section? Elementary school.

In solid geometry, cross section refers to a plane figure obtained by cutting a geometric body (including cylinder, cone, sphere, prism, pyramid, cuboid, cube, etc.). ) with a plane. The geometric cross-section can be circular, elliptical or polygonal, such as trapezoid, triangle, quadrilateral, hexagon and so on.

Generally, geometric sections are classified according to the relative position between the plane where the section is generated and the cutting geometry. Specifically, it is classified according to the relative position of the plane and the height line, symmetry axis or bottom surface of the truncated geometry.

1. Cross section: First, the cross section is a cross section; Secondly, it refers to cutting the geometry horizontally. The cross section has the requirement of "cutting" in the specified direction. Cut from a specific direction. For example, the cross section of a cylinder or cone is usually circular. Another example is that the cross section of a cuboid is generally rectangular. In practical problems, the dam sections of rivers and reservoirs can generally be regarded as trapezoidal.

2. Flat section: generally refers to the section parallel to the bottom of the geometry.

3. Straight section: generally refers to the section perpendicular to the height line or symmetry axis of the geometric figure.

4. Oblique section: generally refers to a section that forms a certain angle with the high line or symmetry axis of the geometry.