a quick trig proof?

Question

a quick trig proof?

anonymous · Answer

$$prove$$ 
$$\frac{ \sin2x - \cos2x }{ \sin2x + \cos2x} = \tan2x$$

isaiah.feynman · Answer

Quick huh?

anonymous · Answer

yeah, i remember there are just 3 or 5 steps max... but i dont remember... i guess you begin by dividing the num and denom by cos2x

anonymous · Answer

and in the end you (probably) use the formula tan2x= 2tanx/ 1 - tan²x ....but i can´t remember the steps in between

isaiah.feynman · Answer

My way is long. So can't quickly do this now.

anonymous · Answer

well no probs!! whatever gets this proved! long or short doesnt matter...

anonymous · Answer

@mathstudent55 will you please make up your mind?!? im getting so restless here, because i can´t remember this solution ^-^

anonymous · Answer

pleeease!!!! anyone!!!

mathstudent55 · Answer

Are you sure you copied this proof correctly?
I'm not sure this is a true identity.

anonymous · Answer

wait a sec, i´ll give you the complete question:

anonymous · Answer

differentiate
$$\tan ^{-1}\left(  \frac{ \sin2x - \cos2x }{ \sin2x +\cos2x }\right)$$
with relation to x

anonymous · Answer

and the answer given is 2

mathstudent55 · Answer

I don't know. My suggestion is for you to start a new post with the question as you asked now.