cos^2π/12-sin^2π/12等于
2sin@+cos@等于?
(cosπ/12-sinπ/12)*(COSπ/12+sinπ/12)等于
cos(2/7π-α)等于sin多少
cos(7π/2-α)等于-sinα吗
cos(7π/2-α)等于sin多少
sin@2-cos@2等于
sinπ/24*cosπ/24*sinπ/12=—— 答案是这么写的:1/2(2sinπ/24*cosπ/24)cosπ
cos(α+π/4)为什么等于根号2/2cosα-根号2/2sinα?
若sinα+cosαsinα−cosα=2,则sin(α-5π)•sin(3π2-α)等于( )
若(sinθ+cosθ)/(sinθ-cosθ)=2,则sin(θ-5π)*sin(3π/2-θ)等于?
sin(2分之π + α)= cosα 那sin(2分之π - α) = cosα 还是等于 -cosα?
已知sin(2π-α)=45,α∈(3π2,2π),则sinα+cosαsinα-cosα等于( )