若函数f(x)=sin^2 x,则f(π/12)=----------- ,单调增区间是---------
问题描述:
若函数f(x)=sin^2 x,则f(π/12)=----------- ,单调增区间是---------
答
f(x)=sin^2 x
f(π/12)=sin²(π/12)=(1-cosπ/6)/2=(1-√3/2)/2=(2-√3)/4
f(x)=(1/2)(1-cos2x)
=-(1/2)cos2x+1/2
单增:
2x∈[2kπ,2kπ+π]
x∈[kπ,kπ+π/2] k∈z