已知α,α+β≠kπ+π/2(k∈Z),且sin(2α+β)+2sinβ=0,求证tanα=3tan(α+β)
问题描述:
已知α,α+β≠kπ+π/2(k∈Z),且sin(2α+β)+2sinβ=0,求证tanα=3tan(α+β)
答
sin(2α+β)+2sinβ=0sin(2α+β)=-2sinβsin(α+β+α)=-2sin(α+β-α)sin(α+β)cosα+cos(α+β)sinα=-2[sin(α+β)cosα-cos(α+β)sinα]sin(α+β)cosα+cos(α+β)sinα=-2sin(α+β)cosα+2cos(α+...