求下列各三角函数值:(1)sin(-1920°) (2)cos(-1560°) (3)tan(-17π/6)

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/01 07:23:07

求下列各三角函数值:(1)sin(-1920°) (2)cos(-1560°) (3)tan(-17π/6)
求下列各三角函数值:(1)sin(-1920°) (2)cos(-1560°) (3)tan(-17π/6)

求下列各三角函数值:(1)sin(-1920°) (2)cos(-1560°) (3)tan(-17π/6)
sin(-1920°)=sin(-1920°+360°*6)=sin(240°)=-√3/2
cos(-1560°)=cos(-1560°+360°*5)=cos(240°)=-1/2
tan(-17π/6)=tan(-17π/6+π*3)=tan(1/6π)=√3/3

(1)=sin(-360°*5-120°)=sin(-120°)=-sin60°=- (根号3)/2
(2)=cos1560°=cos(360°*3+120°)=cos120°=-1/2
(3)=tan(-18π/6+π/6)=tan(π/6)=根号3

cos9π/4=cos(2π+π/4)=cosπ/4=根号2/2 sin780°=sin(720°+60°)=sin60°=根号3/2 tan(-7π/6)=tan(-2π+5π/6)=tan(π-