已知向量a=(sin2x,cos2x)向量b=(1/2,-((√3)/2)),f(x)=a·b,x∈[π/6,7π/6]
已知向量a=(sin2x,cos2x)向量b=(1/2,-((√3)/2)),f(x)=a·b,x∈[π/6,7π/6]若-1<f(x)<0,
已知向量a=(sin2x,cos2x)向量b=(1/2,-((√3)/2)),f(x)=a·b,x∈[π/6,7π/6]
(I)若-1<f(x)<0,求x的取值范围
(II)若方程f(x)=a(-1<a<0)的两根分别为x1,x2,试求sin(x1+x2)值