题干
若0<α<
,-
<β<0,cos
+α
,cos
-
，，则cos α+
=____
| 2 |
| 2 |
| 4 |
| 1 |
| 3 |
| 4 |
| β |
| 2 |
| 3 |
| 3 |
| β |
| 2 |
答案(点此获取答案解析）
| 5 |
| 3 |
| 9 |
| 2 |
| 2 |
| 4 |
| 1 |
| 3 |
| 4 |
| β |
| 2 |
| 3 |
| 3 |
| β |
| 2 |
| 5 |
| 3 |
| 9 |
