在立体几何中 ,二面角的有关概念、二面角的求法 ,既是学习的重点 ,又是难点 .学生在解决二面角的问题时 ,常感到图难画 ,角不好找 .有时 ,角虽作出却不易或无法求出 .如何克服这一难点呢 ?其实 ,只要掌握好二面角的有关概念、二面角的平面角的作法 ,在读懂题的基础上 ,从“找? In the three-dimensional geometry, the concept of the dihedral angle and the method of dihedral angle are both the focus of study and the difficulty. When students solve the dihedral problem, they often find it difficult to draw and the corner is not easy to find. Sometimes, Although the angle is not easy to make or cannot be found, how to overcome this difficulty? In fact, as long as you have a good grasp of the concept of the dihedral angle and the practice of the dihedral plane angle, on the basis of reading the problem, from the “Find?