周期现象是客观世界常见的基本现象,周期函数是刻画周期现象的函数模型,而三角函数又是重要的周期函数,因此,中学数学教材主要利用三角函数研究周期现象.而三角函数的研究中,重点应放在对正弦函数的研究上,余弦函数和正切函数,无论图像还是性质,研究方式方法都与正弦函数的研究过程基本相同.北师大版教科书必修④(以下简称教材),对“正弦函数的性质”的研究,可谓独具匠心,一线教师若不 Cyclical phenomenon is a common basic phenomenon in the objective world. Cyclical function is a function model that describes the periodic phenomenon. Triangular function is an important periodic function. Therefore, the secondary mathematics textbook mainly uses trigonometry to study the periodic phenomenon. In the study of trigonometric function, The emphasis should be placed on the study of the sine function, the cosine function and the tangent function, regardless of the image or the nature of the research methods and methods are basically the same sinusoidal function research process. 北 师大 版 教育书 必修 ④ (hereinafter referred to as teaching material) “The nature of the sine function ” research, can be described as originality, first-line teachers if not