若方程coa2x-2√3sinxcosx=k+1有解,则k的取值范围s

题目

若方程coa2x-2√3sinxcosx=k+1有解,则k的取值范围s

答案

cos2x-2√3sinxcosx
=cos2x-√3sin2x
=2(cos60°cos2x-sin60°sin2x)
=2cos(2x+60°)
=k+1
-1≤(k+1)/2≤1
-3≤k≤1