cos(π/6+3x)=sin（π/2-（π/6+3x））=sin(π/3-3x)

已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值第一题1/2cos x-√3/2sin x第二题√3sin x+cos x第三题√2[sin x-cos x]第四题√2cos x-√6sin x 为什么cos(2x-π/3)-sin(5π/6) =cos(2x-π/3)? cos(π/6-x)=sin(π/3+x)?为什么 求证 tan（2π-X）sin（-2π-X）cos（6π-X）/ sin（X+3π/2)*cos（X+3π/2)=-tanX 已知函数f（x）=［2sin（x-π/6）+√3sin x］cos x+sin^2x,x∈R 已知F(X)=根号3COS^2 X+SIN XCOS X-2SIN X*SIN(X-π/6),求F(X)的最大值 函数Y=sin(2x+π/3)cos(x-π/6)-cos(2x+π/3)sin(x-π/6)的图像的一条对称轴方程是多少 已知sin(x+π/3)=1/4,求sin(2π/3-x)+cos²(π/6-x) cos (2x-π/3)=2sinπ/4 若sin(π+x)+cos(π/2+x)=-m,则cos（3π/2-π）+2sin（6π-x）=? 为什么sinˆ6 +cos ˆ6=sinˆ6(x+π/2)+cosˆ6(x+π/2) 化简sin(x+7π/4)+cos(x-3π/4）步骤我已经找到撒sin(x+7π/4)+cos(x-3π/4)=sin(x+2π-π/4)+cos(x-π+π/4)我问下这一步是在干嘛?=sin(x-π/4)+cos[-(π-x-π/4)]=sin(x-π/4)+cos(π-x-π/4)=sin(x-π/4)-cos(x+π/4)=sin(x-π/4)-cos(x+π/2- 由cos(a+b)=cos a cos b-sin a sin b cos(a-b)=cos a cos b+sin a sin b解题设a为锐角,证：1、2分之根3乘cos a + 2分之1乘sin a=cos(6分之π-a)2、cos a-sin a=根号2cos(4分之π+a) 1.化简根号2cos x - 根号6sin x2.已知sin(α-β)cosα-cos(β-α)sinα=3/5,β是第三象限角,求sin(β+5π/4)的值.3.化简sin(α-β)sin(β-λ)-cos(α-β)cos(λ-β) 函数y=cos^2(3x+π/6)-sin^2(3x+π/6)化简 sin（π/6+x）=1/3 cos（2π/3-2x）=? y=sin(2x-π/6)-3cos(2x-π/6)的值域 sin（x+π/6）=3/5,则cos(2x+π/3)=