问题
填空题
函数f(x)=cos(2x-
|
答案
函数f(x)=cos(2x-
π |
3 |
π |
4 |
π |
4 |
=cos(2x-
π |
3 |
π |
4 |
π |
2 |
π |
4 |
=cos(2x-
π |
3 |
π |
4 |
π |
4 |
=cos(2x-
π |
3 |
π |
2 |
=cos(2x-
π |
3 |
=cos2xcos
π |
3 |
π |
3 |
=
| ||
2 |
1 |
2 |
=sin(2x-
π |
6 |
∵ω=2,∴T=
2π |
2 |
由正弦函数的单调减区间为[2kπ+
π |
2 |
3π |
2 |
得到2kπ+
π |
2 |
π |
6 |
3π |
2 |
解得kπ+
π |
3 |
5π |
6 |
则函数f(x)的单调减区间为[kπ+
π |
3 |
5π |
6 |
故答案为:π;[kπ+
π |
3 |
5π |
6 |