The polygons surrounding a polyhedron are called faces of the polyhedron, the common edges of two adjacent faces are called edges of the polyhedron, and the common points between edges are called vertices of the polyhedron.

In a polyhedron, the line segment connecting two vertices on the same face is called the diagonal of the polyhedron if it is not an edge of the polyhedron. The line segment connecting two vertices on the same face is called the diagonal of the polyhedron. , the plane figure obtained by intersecting a geometric body with another plane is called the cross section of this geometric body

Two faces are parallel to each other, and the vertices of the polyhedron are on these two faces, and all other faces are parallelograms. Such a polyhedron is called a prism.

The two mutually parallel surfaces are called the ground, the other surfaces are called the sides of the prism, and the common side of the two sides is called the side edge. It is obtained by drawing a perpendicular to the other base through any vertex on the ground of the prism. The line segment is height. If the side edges of the prism are perpendicular to the ground, it is called a right prism. A right prism with a regular polygon on the ground is called a regular prism.

If one face of a polyhedron is a polygon, and the other faces are triangles with a common vertex, it is called a pyramid - the polygon face is called the pyramid ground, and the triangles with common vertices are called the sides of the pyramid. The common point of the pyramid is called the vertex of the pyramid, and the common sides of the adjacent two sides are called the side edges of the pyramid. If the line connecting the vertex and the center of the ground is perpendicular to the ground, it is called a right pyramid. The height of the isosceles triangle on the side is called the sloping height.

Use a plane parallel to the pyramid ground to truncate the pyramid. The polyhedron between the cross section and the ground is called a prism. The base and cross section of the original pyramid are called the lower base and the upper base respectively. The other faces are called the sides of the prism. The two adjacent sides The common sides of are called side edges. A prism can be represented by the vertices of the upper and lower bases. The line segment obtained by passing through any vertex on one base of the prism and drawing a perpendicular to the other base is called the height of the prism. A regular pyramid The intercepted prism is a regular prism

The distance to a fixed point in space is equal to a set of fixed length