A solid whose surface consists of some (planar) polygons is called a polyhedron. A polyhedron without holes is called a simple polyhedron, such as a cuboid, a cube, a triangular pyramid, etc. The surface of a simple polyhedron can form a sphere continuously. As long as its surface is an elastic rubber film, it will expand into a sphere after inflation.

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Geometric graphics are widely used, and they are needed in design, painting creation and mathematical research. Mathematical definitions, theorems, etc. It is very abstract in mathematical language, and it is difficult to remember theorems. If geometric figures and numbers are properly combined in teaching, learners can deepen their understanding of intuitive figures and master their theorems. ?