f（x）＝sinx－cosx最小值

f（x）＝sinx－cosx最小值
f（x）＝sinx－cosx最小值

f（x）＝sinx－cosx最小值
f（x）＝sinx－cosx=√2[√2/2sinx-√2/2cosx]=√2(sinxcosπ/4-cosxsinπ/4)=√2 sin(x - π/4)
所以,f（x）的最大值为√2,最小值为-√2

f(x) = sinx - cosx
= √2 sin(x - π/4)
最小值：-√2

f(x)=√2[(√2/2)sinx－(√2/2)cosx]
=√2[sinxcos(π/4)－cosxsin(π/4)]
=√2sin(x－π/4)
则：f(x)的最小值是－√2，最大值是√2

负根2