1-tan2a5/1+tan2a=cos2a-sin2a

Dear Rob,

And your question is?

I did trigonometry, but unfortunately failed the mind-reading course...

Maybe this link to Dave's Short Trig Course (http://www.clarku.edu/~djoyce/trig/) will help you. Special attention for chapter 16 : Summary of trigonometric identities.

If not please state clearly with what I can help you...

:)

(1+cos(x))/(sin(x)) + (sin(x))/(1+cos(x))=2 csc(x)

\frac{1+cos(x)}{sin(x)} + \frac{sin(x)}{1+cos(x)}=2 csc(x)

See here:

https://www.askmehelpdesk.com/math-sciences/proving-trigonometric-identities-324123.html