If sinx=3/5,cosy=-12/13,where x and y both lie in 2nd quad.Find the value os sin(x+y).

Answer 1

luckily, you have nice easy 3-4-5 and 5-12-13 triangles.

cosx = -4/5
siny = 5/13

sin(x+y) = (3/5)(-12/13) + (-4/5)(5/13) = -56/65

reasonable, since (x+y) will be in QIII or QIV

Answer 2

I don't know this answer