设cos(π/4+α)=-√3/2(π/2

设cos(π/4+α)=-√3/2(π/2 设f(α)=2sinαcosα+cosα/1+sin²α+cos(3π/2+α)-sin²(π/2+ 设sinθ+cosθ=√2/3,π/2 设α∈(0,π/2),若sinα=4/5,则cos(α-π/3)等于? 设cosα=-√5/5 π 设函数f（x）=cos（x+2/3π）+2cos^2 x/2,x∈R. 设函数fx＝cos﹙2x－4π／3﹚＋2cos²x 设函数f(x)=2cos^2(x+π/6)-cos^2x 设函数f(x)=cos(2x-4π/3)+2cos²x (2)已知ΔABC中,角A,B,C的对边分 设f(x)=e^3x-1×cos(2πx+π/3),求导数 设α为钝角,若sin(α+π/6)=1/3 则cos(2α+π/12)=? 设α使第三象限角,tan(π-α)=-5/12,则cos(3π/2-α)=