二面角是立体几何的一个重要概念,二面角的平面角的求法是立体几何中的一个重点,也是难点,其中以多面体为载体的二面角的计算问题还是一个热点.在此,我们利用极限和函数思想方法来探求一类二面角的取值范围.一、极端化——得出猜想设正n棱锥P-A1A2…An的高为PO(如图1),由正棱锥 The dihedral angle is an important concept of the three-dimensional geometry. The solution of the dihedral plane angle is an important and difficult point in the three-dimensional geometry. The calculation of the dihedral angle with the polyhedron as the carrier is still a hot issue. Here, we Use limit and function thinking methods to search for a range of dihedral angles. First, the extremes - to find the hypothesis of the set of positive pyramids P-A1A2 ... An high PO (Figure 1), from the positive pyramid