Given sin(x) = 3/5 with x in the second quadrant and tan (y) = 12/5 with y in the 3rd quad.

sin (x+y) = 819/65 <----- Is this correct?

cos(x-y) = 728/65 <------ Is this correct?

I also need to fine tan2x using 2tanx/1-tan^2x but got a really jumbled up answer! PLEASE HELP!!!