已知f(α)=sin(α−3π)cos(2π−α)sin(−α+3π2)cos(−π−α)sin(−π−α).
来源:学生作业帮 编辑:百度作业网作业帮 分类:数学作业 时间:2024/04/30 21:57:05
已知f(α)=
sin(α−3π)cos(2π−α)sin(−α+
| ||
cos(−π−α)sin(−π−α) |
(1)f(α)=
sin(α−3π)cos(2π−α)sin(−α+
3π
2)
cos(−π−α)sin(−π−α)
=
−sin(3π−α)•cos(−α)•(−cosα)
cos(π+α)•[−sin(π+α)]
=
−sinα•cosα•(−cosα)
−cosα•sinα=-cosα;
(2)∵α=-
31π
3,f(α)=-cosα,
∴f(α)=-cos(−
31π
3)
=-cos
31π
3=-cos(10π+
π
3)=-cos
π
3=-
1
2.
sin(α−3π)cos(2π−α)sin(−α+
3π
2)
cos(−π−α)sin(−π−α)
=
−sin(3π−α)•cos(−α)•(−cosα)
cos(π+α)•[−sin(π+α)]
=
−sinα•cosα•(−cosα)
−cosα•sinα=-cosα;
(2)∵α=-
31π
3,f(α)=-cosα,
∴f(α)=-cos(−
31π
3)
=-cos
31π
3=-cos(10π+
π
3)=-cos
π
3=-
1
2.
已知sin(3π−α)=−2sin(π2+α),则sinαcosα=( )
若sinα+cosαsinα−cosα=2,则sin(α-5π)•sin(3π2-α)等于( )
已知tanα=2,求sinα−3cosαsinα+cosα
已知sin(α-π)=2cos(2π-α),求sin(π−α)+5cos(2π−α)3cos(π−α)−sin(−α)
已知sinα=2cosα,求sinα−4cosα5sinα+2cosα
已知sinα−2cosα3sinα+5cosα=−5
已知(3sinα+cosα)/(3cosα-sinα)=2,则2-3sin(α-3π)sin(1.5π-α)-[cos(
已知tanα=3,求2cos(π−α)−3sin(π+α)4cos(−α)+sin(2π−α)
化简:(1)sin(α+β)−2sinαcosβ2sinαsinβ+cos(α+β)
已知sinα=23,则cos(3π−2α)等于( )
已知α为锐角,tanα=3,求sinα−cosαsinα+2cosα
若4sinα−2cosα5cosα+3sinα=10