Question

y=sin2x/（1-sinx-cosx）+sin2x的值?

Answer 1

sin2x=2sinxcosx=(sinx+cosx)^2-1=(sinx+cosx+1)(sinx+cosx-1),然后我们令sinx+cosx＝t,则y=[(t+1)(t-1)/(1-t)]+[(t+1)(t-1)]=(t+1)(t-2),容易求得t的取值范围是－根号2