赞 liuyong8107 花朵
共回答了14个问题采纳率：92.9% 举报
tan(-1560º)cos(17π/6)=tan(-1800º+240º)cos(17π/6-2π)=tan(240º)cos(5π/6)=tan(180º+60º)×cos(5π/6)=tan60ºcos(5π/6)=(√3)×(-√3/2)=-1.5
1年前
1
mozhangwei1 幼苗
共回答了263个问题 举报
tan(－1560°)cos(17π/6)
=tan(－360°×5+240°)cos(2π+(5π/6))
=tan240°cos(5π/6)
=tan(240°π/180°)cos(5π/6)
=tan(4π/3)cos(5π/6)
=tan(π+(π/3))×cos(π-(π/6))
=tan(π/3)×(-cos(π/6))
=√3×(-√3/2)
=-3/2
=tan(－360°×5+240°)cos(2π+(5π/6))
=tan240°cos(5π/6)
=tan(240°π/180°)cos(5π/6)
=tan(4π/3)cos(5π/6)
=tan(π+(π/3))×cos(π-(π/6))
=tan(π/3)×(-cos(π/6))
=√3×(-√3/2)
=-3/2
1年前
0
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