问题:
|
a
|=4,|
b
|=5,|
a
+
b
|=8,则
a
与
b
的夹角为______.
|
|=4,|
|=5,|
+
|=8,则
与
的夹角为______.
a |
b |
a |
b |
a |
b |
参考答案: