cosπ/5cos2π/5=?
COSπ/5乘以COS2π/5
求COSπ/5*COS2π/5
cosπ/5·cos2π/5等于多少?
(cosπ/5)(cos2π/5)的值等于
cosπ/5 乘以cos2π/5等于多少
cosπ/5*cos2π/5 =(2sinπ/5*cosπ/5*cos2π/5)/(2sinπ/5) =(sin2π/5
(二倍角的三角函数)cosπ/5cos2/5π的值是______cosπ/5cos2π/5 =sinπ/5cosπ/5c
已知5cos2α+4cos2β=4cosα,则cos2α+cos2β的取值范围是______.
已知sin(π/4-α)=5/13,α∈(0,π/4) 求cos2α/cos(π/4+α)
已知sinα+cosα=1/5,且π/2≤α≤3π/4,求cos2α
已知α是第四象限角 且cosα=5/13 求sin(α+π/4)/cos2α
cos派/5cos2派/5