Well guys, I really would appreciate it were someone able to prove to me this:

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

I think the left side equals cos(2x), but I'm not even sure of that! Any help is much appreciated! (Happy)

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- November 8th 2009, 09:35 AMsaintvTrigonometric Identity - All that Good Stuff!
Well guys, I really would appreciate it were someone able to prove to me this:

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

I think the left side equals cos(2x), but I'm not even sure of that! Any help is much appreciated! (Happy) - November 8th 2009, 09:41 AMadkinsjr
- November 8th 2009, 09:43 AMe^(i*pi)
- November 8th 2009, 10:00 AMsaintv
Thank you so much, both of you! I really understand it now! :)

Guess I need to work on the algebraic skills a bit more.