三角函数定义是三角函数知识的基础,也是进行三角函数证明、化简、求值的重要依据。三角函数的定义除了用来求解有关三角函数的问题,在单位圆、平面向量、旋转问题等题目的解答中也有着广泛的应用。因此,同学们要深刻理解三角函数的定义,抓住问题的本质,妙用三角函数的定义解题,从而拓宽数学思维。一、善用三角函数定义证明三角恒等式三角恒等式是高中数学学习的重点和难点,它具有公式多、运算符号复杂、角度和函数名称变化灵活的 The definition of trigonometric function is the basis of trigonometric function knowledge, which is also an important basis for trigonometric function to prove, simplify and evaluate. In addition to the definition of trigonometric functions used to solve the problem of trigonometric functions, the unit circle, planar vectors, rotation problems and other topics also have a wide range of applications. Therefore, students should have a profound understanding of the definition of trigonometric functions, seize the essence of the problem, and use the definition of trigonometric functions to solve problems so as to broaden the mathematical thinking. First, make good use of trigonometric function definition Prove the triangle equality Trigonometric identity is the high school mathematics learning focus and difficulty, it has many formulas, the operation symbol is complex, the angle and function name change is flexible