Question

How to verify this identity? : tan(x/2)= sinx/1+cosx

Answer 1

Proof

Explanation:

We have
`sin(x)/(1+cos(x))`
Using that
`sin(x)=2sin(x/2)*cos(x/2)`
and

`cos(x)=2cos^2(x/2)-1`
then

`(2sin(x/2)cos(x/2))/(2cos^2(x/2)-1+1)=tan(x/2)`