f(x)=sin2x×
+1 2
cos2x+
3
2
sin2x?1 2
cos2x+cos2x
3
2
=sin2x+cos2x
=
sin(2x+
2
)π 4
(1∵0∴
T=
=π2π 2
(2)由f(x)可以看出函数f(x)的增区间为
2x+
∈[?π 4
+2kπ,π 2
+2kπ]π 2
即函数f(x)的增区间为:[-
+kπ,3π 8
+kπ]k∈Zπ 8
(3)∵x∈[-
,π 4
]π 4
∴2x+
∈[?π 4
,π 4
]3π 4
根据正弦函数的增减区间可知:
当2x+
=-π 4
时,f(x)min=-1;π 4
当2x+
=π 4
时f(x)max=π 2