证明cos2β-cos2α=sin(α+β)sin(α-β)
已知cos2α-cos2β=m,那么sin(α+β)sin(α-β)=______.
2sinα=sinθ+cosθ,sin²β==sinθcosθ.求证cos2β=2cos2α=2cos
已知sinθ+cosθ=2sinα,sinθ·cosθ=sin²β,求证:2cos2α=cos2β.
已知sinθ+cosθ=2sinα,sinθcosθ=(sinβ)^2,求证4(cos2α)^2=(cos2β)^2
三角数列题:sinθ sinα cosθ成等差数列,sinθ sinβ cosθ为等比数列,求证2COS2α=cos2β
已知sin(α+β)sin(α-β)=3分之1 求cos2β-cos2α的值,4分之1 sin2α方+sinβ方+cos
求证2sin(α-2β)sin(α+2β)=cos4β-cos2α
Sin²αSin²β+Cos²αCos²β-1/2Cos2αCos2β
化简:sin^2αsin^2β+cos^2αcos^2β-1/2cos2αcos2β
化解sin^2αsin^2β+cos^2αcos^2β-1/2cos2αcos2β
化简:sin²αsin²β+cos²αcos²β-1/2cos2αcos2β
化简(sinα)^2*(sinβ)^2+(cosα)^2(cosβ)^2-1/2cos2αcos2β