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About LinkBacksprove 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!!!
help on proving trig identity
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!!!
oh wow thanksOriginally Posted by Grandad
Hello ladythugetteYou're doing great so far!
Now use
on the top, and
on the bottom, and you're there!
Grandad!!!.. i'm definitely going to remember those two equations before my exam. i keep thinking that cosθ can not be changed unless there is a number infront of θ, then i'd know to use the double angle formulae for cos
Grandad did use the double angle formulaoh wow thanks
 = cos\left(\frac{\theta}{2} + \frac{\theta}{2}\right) = cos \left(2\, \frac{\theta}{2}\right))
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