cosπ/5*cos2π/5 =(2sinπ/5*cosπ/5*cos2π/5)/(2sinπ/5) =(sin2π/5
cosπ/5*cos2π/5 =(2sinπ/5*cosπ/5*cos2π/5)/(2sinπ/5) =(sin2π/5
已知sin2α-cos2α+1/sinα+cosα=5分之根号10,α属于(0,π/2),求sinα和tan(2α+
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(二倍角的三角函数)cosπ/5cos2/5π的值是______cosπ/5cos2π/5 =sinπ/5cosπ/5c
sinπ.cosπ.sin2π.cos2π分别是多少
已知tan(π/4+α)=2 求(cos2α-sin2α)/(2sinαcosα+cos^2α)
已知sinα+cosα=1/5,且π/2≤α≤3π/4,求cos2α
COSπ/5乘以COS2π/5
求COSπ/5*COS2π/5
若sin(π/4+α)=sinθ+cosθ,2sin^2β=sin2θ,求证:sin2θ+2cos2β=3
已知sinα=5/13,α∈(π/2,π)求sin2α,cos2α,tan2α的值
已知sinα=3/5,α∈(π/2,π),求sin2α,cos2α的值