π/2<2x+π/3<2π/3 如何变成 ?<sin(2x+π/3)<?

问题描述:

π/2<2x+π/3<2π/3 如何变成 ?<sin(2x+π/3)<?

设函数f(x)=sin(2x+π/3)
定义域为 π/2<2x+π/3<2π/3
因为sinx在π/2<x<2π/3上是减函数
所以sin3π/2<sin(2x+π/3)<sinπ/2
即√3/2 <sin(2x+π/3)<1