题目

设θ∈［0，2π］，利用三角函数线求θ的取值范围.（1）tanθ＞-1;(2)cosθ＜;(3)-≤sinθ＜. 答案：解：如图（1）tanθ＞-1θ∈［0,)∪(,)∪(,2π).(2)cosθ＜θ∈(,).    (3)-≤sinθ＜θ∈［0，)∪(,］∪［,2π］.This pet shop is losing its customers ______ its staff work slowly and often make mistakes.A. so B. because C. until D. although