函数的周期为______________.
已知sin=,则cos=________.
已知sinθ+cosθ=,且≤θ≤,则cos2θ=________.
已知sin2α=,则cos2=________.
设α为锐角,若cos=,则sin(2α+)=__________.
已知向量a=(sinθ,cosθ),b=(3,-4),若a∥b,则tan2θ=__________.