Question

已知tana/2=2,求： (6sina+cosa)/(3sina-2cosa)的值

Answer 1

tana=2tana/2/[1-(tana/2)^2] 所以tana=4/(1-4)=-4/3 故(6sina+cosa)/(3sina-2cosa) =(6+ctga)/(3-2ctga) =(6-3/4)/(3+3/2) =(21/4)/(9/2) =7/6