函数f(x)=sinx+cosx的单调递增区间是__

问题描述:

函数f(x)=sinx+cosx的单调递增区间是__

f(x)=sinx+cosx
=√2(√2/2*sinx+√2/2cosx)
=√2(sinxcosπ/4+cosxsinπ/4)
=√2sin(x+π/4)
递增则2kπ-π/2