已知函数f(x)=2sin^2x+2根号3sinxcosx+1,求f(x)的最小正周期,单调区间,最值

最值是在【0,π⼀2】上的最值
2024-12-17 13:30:28
推荐回答(1个)
回答1:

f(x)=2(1-cos2x)/2+√3(sin2x)+1
=√3sin2x-cos2x+2
=2sin2xcosπ/6-2cos2xsinπ/6+2
=2(sin2xcosπ/6-cos2xsinπ/6)+2
=2sin(2x-π/6)+2
所以T=2π/2=π

增函数时2kπ-π/2<2x-π/6<2kπ+π/2
所以增区间(kπ-π/6,kπ+π/3)
同理,减区间(kπ+π/3,kπ+5π/6)

sin(2x-π/6)最值是±1
所以最大=4,最小=0