prove the following identity:
Secθ- 1/ Secθ +1 ≡ Tan² θ/2 (only the theta is divided by 2)
this is what i've done so far:
LHS =( secθ- 1)/ (secθ +1)
= (1/cosθ - 1) /(1/cosθ +1 )
= 1- cosθ/ 1+ cosθ
from here, I don't know what to do next. help plz!!!