Question

1.知sin(x/2) - 2cos(x/2)=0,求tan x ,sin x ,cos x'

Answer 1

sin(x/2) - 2cos(x/2)=0

sin(x/2) =2cos(x/2)

sin(x/2) /cos(x/2)=2

tan(x/2)=2

tanx=2tanx/2/[1-(tanx/2)^2]

tanx=2*2/[1-2^2]

tanx=-4/3

sinx=4/5,cosx=-3/5或sinx=-4/5,cosx=3/5

180