Trigonometric Identities

can you tell me the easiest way to answer the trigo identities problem?

To make sure I understand what you're asking for, you would like to have the calculator help you with simplifying trigonometric expressions. For example the following:

sin(a)cos(b)+cos(a)sin(b)

can be simplified to:
sin(a+b)

A complete list of trigonometric identities can be found here:

http://en.wikipedia.org/wiki/Trigonometric_identity

To answer your question, currently there are no trigonometric identities features included in Smart Math Calculator to perform the above. We are however considering to add those to our Smart Math Calculator problem for future versions. If you like to see this feature added please post your agreement in this forum. It would also help if you include with your post an example of a trigonometric identity that you like to see this calculator solve.