Question

sina=3/5,a∈(∏/2,∏),tanℓ=-1/2,则tan(a-ℓ)等于多少？

sina=3/5,a∈(∏/2,∏),tanℓ=-1/2,则tan(a-ℓ)等于多少

Answer 1

解由sina=3/5,a∈(∏/2,∏),
知cosa=-4/5
则tana=sina/cosa=-3/4
则tan(a-ℓ)
=(tana-tanℓ)/(1+tanatanℓ)
=(-4/5-(-1/2))/(1+(-4/5)(-1/2))
=(-4/5+1/2)/(1+2/5)
=(-8+5)/(10+4)
=-3/14.