Ответ:

sin(x+y)=+-3√13/13

Объяснение:

sinx+siny=2sin(x+y)/2*cos(x-y)/2=1/2

cosx+cosy=2cos(x+y)/2*cos(x-y)/2=1/3

(1/2)/(1/3)=tg(x+y)/2

tg(x+y)/2=sin(x+y)/(1+cos(x+y))

sin(x+y)=t

cos(x+y)=√(1-t²)

3/2=t/√(1-t²)

13t²=9

t=±3√13/13