- 已知角α终边上一点P(-4,3),那么sin(π+α)=( )A.35B.-35C.-1D.45
- 已知sinθ+cosθ=-53,则cos(2θ-7π2)的值为( )A.49B.29C.-29D.-49
- 设函数f(x)=3sinx-sin(π2-2x)sin(π2-x)cos(π+x).(Ⅰ)求f(x)的最值;(Ⅱ)当θ∈(0, π2)时,若f(θ)=1,求θ的值.
- 已知α为第四象限的角,且sin(π2+α)=45,则tanα=( )A.-34B.34C.-43D.43
- 已知sin(π-α)=-2sin(π2+α),则tanα=______.
- 已知角α的终边经过点P(45,-35)(1)求sinα;(2)求sin(π2-α)sin(π+α)•tan(α-π)cos(3π-α)的值.
- 若sin(π3-a)=13,则cos(π3+2a)( )A.-79B.-13C.13D.79
- α∈(-π2,0),sinα=-35,,则cos(π-α)的值为( )A.-45B.45C.35D.-35
- 在三角形ABC,已知tanA+B2=sinC,下列四个论断中正确的是( )①tanA•cotB=1; ②0<sinA+sinB≤2; ③sin2A+cos2B=1; ④cos2A+co...
- 若sinx=sin(3π2-x)=2,则tanx+tan(3π2-x)的值是( )A.-2B.-1C.1D.2
- 化简sin(θ-5π)tan(3π-θ)•1tan(θ-3π2)tan(π2-θ)•cos(8π-θ)sin(-θ-4π)+sin(-θ)
- 已知α是锐角,且tan(α+π4)=3,求sin2α•cos(α+π)-sin(α-π)sin(2a+π2)•cos(2a-π2)的值.
- 已知:f(a)=sin2(π-a)•cos(2π-a)•tan(-π+a)sin(-π+a)tan(3π-a),(1)化简f(a);(2)若a=54π,求f(a)的值;(3)若f(...
- 已知a∈(-π2,0),sina=-35,则tan(π-a)=______.
- 已知sinα=35,则sin(π2+α)的值为( )A.±45B..-45C..45D..-35