The relationship between the number of fixed vertices (V), the number of faces (F) and the number of edges (E) of prisms, pyramids and frustums.

Prism: the relationship between the number of faces and the number of vertices: F=V/2+2,

The relationship between the number of edges and the number of vertices: E=V+V/2=3V/2,

The relationship between the number of edges and the number of faces: E=3F-6.

Type III synthesis: E=V+F-2.

Prisms are like prisms.

Pyramid: the relationship between the number of faces and the number of vertices: F=V,

The relationship between the number of edges and the number of vertices: E=2*(V- 1),

The relationship between the number of edges and the number of faces: E=2*(F- 1). ,

Synthesize three formulas: E=V+F-2.

The formula of prism, prism and pyramid is the same, V+F-E=2,

This is the Euler formula of polyhedron.