题目内容
若
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【答案】分析:根据题中的条件得到cosα>0,根据y=cosx的图象得到α的取值范围即可.
解答:解析:∵
=
=
,
∴cosα>0.∴α∈(2kπ-
,2kπ+
)(k∈Z).
故答案为:α∈(2kπ-
,2kπ+
)(k∈Z)
点评:考查学生三角函数中的恒等变换应用的能力,以及对余弦函数图象的灵活掌握能力.
解答:解析:∵



∴cosα>0.∴α∈(2kπ-


故答案为:α∈(2kπ-


点评:考查学生三角函数中的恒等变换应用的能力,以及对余弦函数图象的灵活掌握能力.

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