问题:
|
a
|=2,|
b
|=3,|
a
+
b
|=4,则
a
与
b
的夹角是______.
|
|=2,|
|=3,|
+
|=4,则
与
的夹角是______.
a |
b |
a |
b |
a |
b |
参考答案: