con2a+sina

It looks like you have an expression that possibly needs to be simplified or solved. The expression \( \cos(2a) + \sin(a) \) involves trigonometric functions.

If you need to simplify it, you can use the double-angle identity for cosine:

\[ \cos(2a) = \cos^2(a) - \sin^2(a) \]

However, without additional context (like solving equations or evaluating at specific values), my assistance is limited.

Could you please clarify what exactly you would like to do with the expression \( \cos(2a) + \sin(a) \)?