已知向量a=(2,cosx),b=(sin(x+π/6),2),函数f(x)=a*b

问题描述:

已知向量a=(2,cosx),b=(sin(x+π/6),2),函数f(x)=a*b
(1)求其单调增区间(2)若f(x)=6/5求cos(2x-π/3)的值

(1) f(x)=a*b=2sin(x+π/6)+2cosx=√3sinx+3cosx化成同名函数 f(x)= 2√3sin(x+π/6) (提取系数平方和) 则2kπ-π/2≤x+π/6≤2kπ+π/2 解得 f(x)的单调递增区间是[2kπ-2π/3,2kπ+π/3],k∈Z.(2) f(x...