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

luckily, you have nice easy 345 and 51213 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