题目内容
函数y=sinxcosx+
cos2x-
的图象的一条对称轴是( )
| 3 |
| 3 |
A.x=
| B.x=
| C.x=
| D.x=
|
∵y=sinxcosx+
cos2x-
=
sin2x+
•
-
=
sin2x+
cos2x-
=sin(2x+
)-
令2x+
=kπ+
可得x=
kπ+
令k=0可得满足条件的对称轴为x=
故选C
| 3 |
| 3 |
=
| 1 |
| 2 |
| 3 |
| 1+cos2x |
| 2 |
| 3 |
=
| 1 |
| 2 |
| ||
| 2 |
| ||
| 2 |
=sin(2x+
| π |
| 3 |
| ||
| 2 |
令2x+
| π |
| 3 |
| π |
| 2 |
| 1 |
| 2 |
| π |
| 12 |
令k=0可得满足条件的对称轴为x=
| π |
| 12 |
故选C
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