在解决三角函数的有关问题时 ,求值 ,尤其是求角是常见的题型 ,其解一般具有唯一性 .为避免增解 ,需要缩小角的范围 .如何缩角 ,学生常常感到很困惑 .本文从以下 6个方面阐述“缩角”的有关方法 ,以提高学生的思维能力和解题能力 .一、利用已知条件“缩角”三角函数问题不但公 When solving problems related to trigonometric functions, evaluation, especially commutation, is a common problem type. Its solution is generally unique. To avoid escalation, it is necessary to reduce the range of angles. How to reduce the angle, students often feel puzzled. This article elaborates the relevant methods of “shrink angle” from the following six aspects to improve the students’ thinking ability and problem-solving ability. First, using the known conditions “angle reduction” trigonometric function is not only public