(Ⅰ)因为f(x)=sin2x-cos2x-1=
sin(2x?
2
)?1.π 4
所以T=
=π.(7分)2π 2
(Ⅱ)f(x)=
sin(2x?
2
)?1π 4
当x∈[0,
]时,?π 2
≤2x?π 4
≤π 4
,3π 4
所以当2x?
=π 4
,f(x)max=π 2
?1,
2
当2x?
=?π 4
,f(x)min=-2.π 4
所以f(x)的取值范围是[?2,
?1].(13分)
2