问题
选择题
函数f(x)=sin(
|
答案
f(x)=sin(
-x 2
)cos(π 3
+x 2
)=sin(π 6
-x 2
)sin[π 3
-(π 2
+x 2
)]π 6
=sin(
-x 2
)sin(π 3
-π 3
)=sin(x 2
-x 2
)sin(π 3
-x 2
)π 3
=
=--cos2(
+x 2
)π 6 2 1+cos(x+
)π 3 2
当x+
∈[-π 3
+2kπ,π 2
+2kπ],k∈Z时,f(x)为增函数π 2
解得-
+2kπ≤x≤π 3
+2kπ,k∈Zπ 3
故选C