Identities for atan(a+b) or atan(a*b)

[rhz]

Hi,

Does anyone know of any nice identities for the inverse or arc tangent of a sum or a product?

Thanks,

rhz

 

[rhz]

bump...

Any ideas out there? I searched for this on google and came up with nothing.

Thanks!

 

[Mentallic]

I don't believe there are any nice expansions for the sum or product of inverse trigs, such as how there are for trigs. What do you need them for exactly?