题目内容
已知sin(α+
)=
,则cos(
-α)=
.
| π |
| 6 |
| 1 |
| 3 |
| π |
| 3 |
| 1 |
| 3 |
| 1 |
| 3 |
分析:由诱导公式可得cos(
-α)=sin[
-(
-α)]=sin(α+
),代入已知可得.
| π |
| 3 |
| π |
| 2 |
| π |
| 3 |
| π |
| 6 |
解答:解:由诱导公式可得cos(
-α)=sin[
-(
-α)]=sin(α+
)=
.
故答案为:
| π |
| 3 |
| π |
| 2 |
| π |
| 3 |
| π |
| 6 |
| 1 |
| 3 |
故答案为:
| 1 |
| 3 |
点评:本题考查三角函数的诱导公式,属基础题.
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已知sin(
-α)=
,则cos(
+2α)=( )
| π |
| 6 |
| 1 |
| 3 |
| 2π |
| 3 |
A、-
| ||
B、-
| ||
C、-
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