- (1)已知tanα=2,求sin(π-α)cos(2π-α)sin(-α+3π2)tan(-α-π)sin(-π-α)的值(2)已知cos(75°+α)=13,其中-180°<α<-90°,求...
- 已知cosθ=13,θ∈(0,π),则cos(π+2θ)等于( )A.-429B.429C.-79D.79
- 已知sin20°=a,则sin290°用a表示为 ______.
- 已知α为第三象限角且sinα=-35,(1)求cosα,tanα;(2)求sin(α-π2)+tan(7π-α)的值.
- 若tanα=2,则sin(π-α)+5cos(2π-α)3cos(π-α)-sin(-α)=______.
- 已知cos(α+π6)=-13,则sin(α-π3)的值为( )A.13B.-13C.233D.-233
- 若π2<α<π,且cosα=-1213,则tan(2π-α)=______.
- 若cos(2π-α)=53且α∈(-π2,0),则sin(π-α)( )A.-53B.-23C.-13D.±23
- 已知tanθ=2,则sin(π2+θ)-cos(π-θ)sin(π2-θ)-sin(π-θ)=( )A.2B.-2C.0D.23
- 已知α∈(0,π),cos(π+α)=45,则tanα=( )A.34B.43C.-34D.-43
- 若sin(3π2-2x)=35,则tan2x=______.
- 已知 tan(π-α)=3,则1sinαcosα______.
- 已知α为锐角,sin(α+3π2)=-55,则tan(α-5π4)=( )A.-3B.3C.13D.-13
- 化简1+2sin290°cos430°sin250°+cos790°=______.
- 已知sin(π+α)=12,求sin(π-α)-tan(-α-π)•sin(π2+α)的值.