二面角是立体几何三大角中难度最大的问题，学生往往因不能正确地作出平面角而使解题搁浅．本文通过一些典型的例题，概括总结出求二面角的平面角的十种常用方法，旨在共同提高解题能力．1应用三角形的性质利用等腰三角形的性质．当二面角是由共底边的两个等腰三角形所组成时， The dihedral angle is the most difficult problem in the three major corners of the three-dimensional geometry. Students often abandon the problem by failing to make the plane angle correctly. In this paper, through some typical examples, the ten common methods for finding the dihedral plane angles are summarized and designed to improve the problem-solving abilities. 1 Apply the properties of a triangle to take advantage of the properties of an isosceles triangle. When the dihedral angle is composed of two isosceles triangles with a common bottom edge,