用诱导公式求下 * * 角函数值:(1)sin(-
|
(1)sin(-
)=sin[-4π+(π+17π 6
)]π 6
=sin(π+
)=-sinπ 6
=-π 6
;1 2
(2)cos(-
)=cos13π 4
=cos[2π+(π+13π 4
)]π 4
=cos(π+
)=-cosπ 4
=-π 4
.2 2
用诱导公式求下 * * 角函数值:(1)sin(-
|
(1)sin(-
)=sin[-4π+(π+17π 6
)]π 6
=sin(π+
)=-sinπ 6
=-π 6
;1 2
(2)cos(-
)=cos13π 4
=cos[2π+(π+13π 4
)]π 4
=cos(π+
)=-cosπ 4
=-π 4
.2 2