向量a与向量b垂直 a.b=sina-√3cosa=0 sina=√3cosa tana=√3 f(x)=sinx+tanacosx =sinx+√3cosx =2(1/2*sinx+√3/2*cosx) =2sin(x+π/3) 函数f(x)单调递增时 x+π/3∈[2kπ-π/2,2kπ+π/2] x∈[2kπ-5π/6,2kπ+π/6] 函数f(x)的单调递增区间:[2kπ-5π/6,2kπ+π/6],k∈Z