2×(sinx)^2+3×cosx大于3,求x的取值范围
问题描述:
2×(sinx)^2+3×cosx大于3,求x的取值范围
答
2(sinx)^2+3cosx=
=2(1-(cosx)^2)+3cosx=
=-2(cosx)^2+3cosx+2>3
(2cosx-1)(cosx-1)