sin(x + y) can be expressed through sine and cosine of x and y. The problem statement gives you the values of cos(x) and sin(y), from where you can find sin(x) and cos(y) taking into account that they are positive.
the instructions state: find the exact value of the expression given that sec x = 3/2, csc y = 3, and x and y are in the quadrant I. sin (x+y) I have no clues as to how to solve this problem from my class notes. Please help if you can. thanks alot