ioi6
幼苗
共回答了21个问题采纳率:95.2% 举报
f(x)=2 cos 2 (x-
π
4 )-[sin(x+
π
4 )+cos(x+
π
4 )] 2
= 1+cos(2x-
π
2 )-[
2 sin(x+
π
2 ) ] 2
=1+sin2x-2cos 2 x=sin2x-cos2x
=
2 sin(2x-
π
4 )
(1)T=
2π
2 =π
(2)当 f(x)取最大值时, sin(2x-
π
4 )=1 ,即 2x-
π
4 =
π
2 +2kπ ⇒{x| x=kπ+
3π
8 ,k∈Z }
1年前
6