若θ∈(0,π),且sinθ+cosθ=1/3,则cos2θ
已知θ∈(0,π)且,sinθ+cosθ=三分之一,则cos2θ=
若1/3sinθ-cosθ=0,则2cos2θ+1/2sin2θ=?
sinθ+sin2θ/1+cosθ+cos2θ=
已知sinθ+cosθ=1/5,且π/2≤θ≤3π/4,则cos2θ的值
若cos2θ=√2/3,则sinθ^4+cos^4的值为
若2sin(π/4+a)=sinθ+cosθ,2sin^2β=sin2θ,求证sin2a+(1/2)cos2β=0
2sinθ+cosθ/sinθ-3cosθ=-5,求cos2θ+4sinθ
sinθ+2cosθ=0,则2cos2θ-sin2θ=
已知6sin^2θ+sinθcosθ-2cos^2θ=0,θ∈[π/2,π]求cos2θ的值
cos2θ=根号2/3,则sin^4θ+cos^4θ=
求证cos^4θ-sin^4θ=cos2θ
cos2θ=√2/3,则cos^4-sin^4的值为