定义域是函数关系中的重要组成部分之一,准确的定义域是解答函数问题的关键.定义域出现错误必然会影响函数问题的解答,我们举一个常见的例子来说明这个问题.三角函数中正弦函数sinx=a,当x∈[π/4,π/2]时,a∈[2~(1/2)/2,1];∈[0,π/2]时,a∈[0,1].因此解决函数问题时学生必须具有严密的思维能力,首先要关注函数定义域取值,才能保证解题准确无误.一、定义域的寻找可以直接运用函数关系式 The definition of domain is one of the most important part of the functional relationship. The accurate definition of the domain is the key to solve the function problem. The definition of domain error will inevitably affect the function of the solution, we give a common example to illustrate this problem. The sine function sinx = a, a∈ [0 ~ π / 2] when a∈ [2 ~ (1/2) / 2,1]; ∈ [0, π / 2] when x∈ [π / 4, π / 2] , 1] .Therefore, to solve the function problem, students must have a rigorous thinking ability, we must first pay attention to the value of the function domain, in order to ensure that the problem is accurate.First, the domain of the search can be directly applied function