长方体、正方体是立体几何中的最易被学生掌握的简单几何体,在长方体中适当添加辅助线,不仅可以构建各种线线关系、线面关系、面面关系,还可以“割出”像三棱锥、四棱锥、直三棱柱、长方体等,所以在解题时,也可以根据题意,将其补为长方体或 The cuboids and cubes are the simple geometry most easily grasped by students in the three-dimensional geometry. Adding auxiliary lines appropriately in the cuboid not only can build various line-line relationships, line-surface relationships, and face-to-face relationships, but also can be used to cut out. Like triangular pyramids, quadrangular pyramids, straight triangular prisms, rectangular solids, etc., so when solving a problem, you can also make up a rectangle or