# Prooving Trig Identities

1. Sep 15, 2006

### ku1005

the follwing trig identity is used alot...but i am unable to proove it because i dont know wat to start with in solving it....

sin2x=2tanx/(tan^2x+1)

it invlves the double angle formulae i know that obviously, i tried substituting sin and cos into the RHS of equation and get my answer down to:

2sinxcox/(1/cos^2x) which is close...i think since sin2x is 2sinxcosx....

does any1 hav any ideas??? LOL...hav any ideas...u already know
appreciate any hints
thanks

2. Sep 15, 2006

### ku1005

damm...evry time i post sumthin on here...i look again at the question and get the answer..soz....

i ended up with
(2tanxcos^2x)/(sin^2x+cos^2x) where abviously the bottom = 1 and at the top the cos x's cancel to leave

2sinxcosx = sin2x

thanks though