(1)f(x)=(cosx+sinx)*(cosx-sinx)+sinx*2cosx
=cos2x+sin2x
=√2/2sin(2x+45度)
所以,T=2π/2=π
(2)x∈[0,π/2]
所以 2x+45度∈[π/4,5/4π]
所以 当 2x+45度=π/2时, 最大=f(π/2)=√2/2
当2x+45度=5π/4时, 最小=f(5π/4)=-1/2x∈[0,π/2]
纯手打,望采纳
追问x∈[-π/4,π/4],
2x+π/4∈[-π/4,3π/4],
sin(2x+π/4)∈[-√2/2,1].
√2sin(2x+π/4)∈[-1,√2]
追答你算错了吧,这题我做过,应该是这个答案,我现在高二