已知sinx=1/3,sin(x+y)=1,则sin(2y+x)= _ .

问题描述:

已知sinx=

1
3
,sin(x+y)=1,则sin(2y+x)= ___ .

∵sin(x+y)=1,
∴x+y=

π
2
+2kπ,k∈Z,
∴y=-x+
π
2
+2kπ,
∴sin(2y+x)=sin(-2x+π+4kπ+x)
=sin(π-x)
=-sinx
=-
1
3

故答案为:-
1
3