已知sinx=1/3,sin(x+y)=1,则sin(2y+x)= _ .
问题描述:
已知sinx=
,sin(x+y)=1,则sin(2y+x)= ___ .1 3
答
∵sin(x+y)=1,
∴x+y=
+2kπ,k∈Z,π 2
∴y=-x+
+2kπ,π 2
∴sin(2y+x)=sin(-2x+π+4kπ+x)
=sin(π-x)
=-sinx
=-
,1 3
故答案为:-
.1 3