已知sin(α+π/2)=1/3,α属于(-π/2,0),则tanα=

Question

已知sin(α+π/2)=1/3,α属于(-π/2,0),则tanα=

Answer 1

因为sin(α+π/2)=cosα=1/3,α∈(-π/2,0)
所以,sinα﹤0
所以,sinα=-√(1-cos²α)=-√(1-1/9)=-2√2/3
tanα=sinα/cosα=(-2√2/3)/(1/3)=-2√2