sin (x+π/4)=cos(π/4-x)=cos(x-π/4)
函数f(x)= cos^2(x-π/4)-sin²(x-π/4)
=cos(2x-π/2)
=sin2x
选B
函数y=1/2sin2x+sin²x
=1/2sin2x+1/2-1/2cos2x
=√2/2 sin(2x-π/4)+1/2
值域[(1-√2)/2,(1+√2)/2]
函数(1+sinx)/(2+cosx)的值域,用斜率法
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函数salon 斜率法求(sinx +√2)/(cosx +√2) 的值域