8sin870°•cos(-660°)•cot(-355°)•tan(-175°)的值是()A.2B.-2C.12D.-12-数学

题目简介

8sin870°•cos(-660°)•cot(-355°)•tan(-175°)的值是()A.2B.-2C.12D.-12-数学

题目详情

8sin870°•cos(-660°)•cot(-355°)•tan(-175°)的值是(  )
A.2B.-2C.
1
2
D.-
1
2
题型:单选题难度:中档来源:不详

答案

因为8sin870°•cos(-660°)•cot(-355°)•tan(-175°)
=8sin(720°+150°)•cos(660°)•cot(355°)•tan(175°)
=8sin150°•cos(720°-60°)•cot(360°-5°)•tan(180°-5°)
=-4cos60°•cot(-5°)•tan5°
=2•cot5°•tan5°
=2.
故选A.

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