问题描述: 已知向量a=(2sinx,2cosx),b=(cosx,sinx) 1个回答 分类:数学 2014-11-01 问题解答: 我来补答 解f(x)=a*b =2sinxcosx+2cos²x =sin2x+2cos²x-1+1 =sin2x+cos2x+1 =√2sin(2x+π/4)+1∴最小正周期为:T=2π/2=π∵x∈[0,3π/8]∴2x+π/4∈[π/4,π]∴sin(2x+π/4)∈[0,1]∴f(x)=√2sin(2x+π/4)+1∈[1,√2+1]∴f(x)的值域为:[1,√2+1] 展开全文阅读