Trig Identities
Proof:
$$\frac{ cosx-sinx }{ cosx+sinx }=\sec2x-\tan2x$$

Question

Trig Identities
Proof:
$$\frac{ cosx-sinx }{ cosx+sinx }=\sec2x-\tan2x$$

anonymous · Answer

Please help! :(

nnesha · Answer

cos = ?
sin = ?

anonymous · Answer

I'm not sure what you mean?

nnesha · Answer

trig identities
sin cos tan properties 
tan = sin /cos 
sin = ?
cos = ?

anonymous · Answer

sin=y/r
cos=x/r

nnesha · Answer

o^_^o $$\rm \sin = \frac{ 1 }{ \csc }$$ $$\rm \cos = \frac{ 1 }{ \sec }$$

anonymous · Answer

ooh...

nnesha · Answer

solve L.H.S replace
 cos by 1/sec 
and sin by 1/csc

ganeshie8 · Answer

that works nicely, there is a shortcut though.. multiply top and bottom by the conjugate of denominator :  `cosx - sinx`

ganeshie8 · Answer

and recall the identity :  $$\cos^2x-\sin^2x=\cos(2x)$$

nnesha · Answer

okay so right 
is that 
$$\large\rm \sec^2 x - \tan^2x  ~~or~ \sec(2x) - \tan (2x)$$
square or 2x ?

anonymous · Answer

2x @Nnesha 
Sorry, I got logged out suddenly and had some difficulty logging back on.

theopenstudyowl · Answer

@ineedhelpnowplz