∴f(x)在R上是奇函數(shù)且是增函數(shù);
∵f(cos2θ-2m)<-f(2msinθ-2)=f(2-2msinθ),
∴cos2θ-2m<2-2msinθ,即cos2θ-2<2m(1-sinθ),
(1)當(dāng)sinθ=1時(shí),∴-2<0恒成立,∴m∈R;
(2)當(dāng)sinθ≠1即1-sinθ>0時(shí),有2m>
cos2θ?2 |
1?sinθ |
?sin2θ?1 |
1?sinθ |
?sin2θ?1 |
1?sinθ |
?(1?sinθ)2+2(1?sinθ)?2 |
1?sinθ |
2 |
1?sinθ |
∵1?sinθ>0∴1?sinθ+
2 |
1?sinθ |
2 |
2 |
∴g(θ)≤?2
2 |
∴2m>2?2
2 |
2 |
綜上有:m的取值范圍是(1?
2 |