已知sinx=1/3,2π

问题描述:

已知sinx=1/3,2π怎么算呀

[sin(x/2)+cos(x/2)]²
=sin²(x/2)+2sin(x/2)cos(x/2)+cos²(x/2)
=1+sinx
=4/3
π第三象限
所以
sin(x/2)sin(x/2)+cos(x/2)所以sin(x/2)+cos(x/2)=-2√3/3