为什么sin(23π/5) = sin(3π/5) ,cos(17π/4) = cos(π/4)?
为什么sin(23π/5) = sin(3π/5) ,cos(17π/4) = cos(π/4)?
已知方程sin(a-3π)=2cos(a-4π),求 [sin(π-a)+5cos(2π-a)]/[2sin(3π/2-
已知sin(a-3π)=2cos(a-4π),求(sin(π-a)+5cos((3π/2)-a))/(2sin(3π/2
sin(π-θ)+cos(2π-θ)/cos(5π/2-θ)+sin(3π/2+θ)=2,则sinθcosθ=_____
已知tan(π-α)=2,求sinα-2sinαcosα-cosα/4cosα-3sinα的值
若(sinθ+cosθ)/(sinθ-cosθ)=2,则sin(θ-5π)*sin(3π/2-θ)等于?
若sinα+cosαsinα−cosα=2,则sin(α-5π)•sin(3π2-α)等于( )
若(sinα+cosα)/(sinα-cosα)=2 则sin(α-5π)·sin(3π/2-α)=?
α属于(0,π/2)且2sin²α-sinαcosα-3cos²α=0求sin(α+π/4)/sin
已知 cos π/5 =(根号5 +1)/4 求 sin π/5,sin -π/5 ,sin 4π/5 ,sin 3π/
已知tan(α+π/4)=3,求cosα+2sinα/cosα-sinα的值
已知(3sinα+cosα)/(3cosα-sinα)=2,则2-3sin(α-3π)sin(1.5π-α)-[cos(