已知cos(π+α)=-3/5,3π/2
已知cosα=1/3,α属于(π,2π),则cosπ/2等于
已知cos(π\3-2)=1\3,则cosα+根号3sinα=
已知cos(π/2+α)=2sin(α-π/2),求[sin^3(π+α)+cos(α+π)]/[5cos(5π/2-α
①化简[sin(2π+α)*cos(7π-α)]/cos(-α)②已知cosθ=-3/5,θ∈(π/2,π),求sin(
已知cosα=-3/5,α属于(π/2,2π)则cos(α-π/4)=
已知sin(5π-α)=√2cos(3π/2+β),)√3cos(-α)=-√2cos(π+β),0
已知cos(α+β)=12/13,cos(2α+β)=3/5,若β∈(0,π/2),求cosα的值.
已知cosα=负5分之3,π
已知sina=2/3 则cos(π-2α)
已知cos(θ+π/4)=3/5,π/2
已知cosα=1/3,且-π/2
已知cos(π/6-a)=根号3/3,求cos(5π/6+a)-cos²(π/3+a)