确定立体几何的有关长度、角、面积、体积的取值范围是立体几何中一类重要题型，在高考及竞赛的试题或训练题中屡见不鲜．由于此类问题条件隐蔽，知识面广而宽，而且涉及到的空间图形复杂多变，因此不易或不可能建立不等式．归纳、研究这类问题的解法，对培养学生分析问题和解 Determining the range of values ​​of length, angle, area and volume of solid geometry is an important type of problem in solid geometry, which is common in examination papers or training questions in college entrance examinations and competitions. Due to the concealment of such problems and the wide and wide range of knowledge, as well as the complex and varied spatial patterns involved, it is not easy or impossible to establish inequalities. Summarize and study the solutions to these problems to train students in problem analysis and solution