# tan2a

1. ### Trig identity, tan(2A)

Have a question i'm having some trouble with, Verify the identity; (sin A + sin 3A) / (cos A + cos 3A) = tan 2A not sure best way to go about this one, tried using sin3A = sin(2A + A) and expanding out but didn't seem to give me anything i wanted. Any help would be greatly appreciated...
2. ### Simplifying an equation involving tan2A forumla

I know this has something to do with the double angle formula for tangent, but I am not sure how to simplify this. Also, is there a way to post math expressions in "pretty print". tan 22.5 / 1-tan^2 22.5 thanks