若sinβ=-5/13,α∈(π/2,π)则cos2α=
若sinβ=-5/13,α∈(π/2,π)则cos2α=
已知sinα=cos2α,α∈(π2
若sin(π/2+α)=3/5,则cos2α=? 急求这道题的解题过程!
已知sin(π/4-α)=5/13 α∈(0,π/4) 求cos2α
若cos2α/sin(α-π/4)=-√2/2,则cosα+sinα的值为?
已知sinα=5/13,α∈(π/2,π)求sin2α,cos2α,tan2α的值
已知sin²2α+sin2αcos2α-cos2α=1,α∈(0,π)求sinα,tanα
已知α∈(π/2,π),且sinα=3/5,则sin^2α/2+(sin4αcos2α)/(1+cos4α)的值为多
cos2α/[sin(α-π/4)]=-根号2 /2,cosα+sinα=?
证明2sin(π/4+α)sin(π/4-α)=cos2α
若sin(π/4+α)=sinθ+cosθ,2sin^2β=sin2θ,求证:sin2θ+2cos2β=3
sinα=cos2α,α∈[π/2,π],求tanα