问题
选择题
已知向量
|
答案
∵|2
+a
|=2，b
∴4
2+4a
•a
+b
2=4，b
∵|
|=1，|a
|=2b
∴
•a
=-1，b
∴向量
在向量b
方向上的投影是a
=-1，-1 |
|a
故选B．
搜题请搜索小程序“爱下问搜题”
已知向量
|
∵|2
+a
|=2，b
∴4
2+4a
•a
+b
2=4，b
∵|
|=1，|a
|=2b
∴
•a
=-1，b
∴向量
在向量b
方向上的投影是a
=-1，-1 |
|a
故选B．
Passage 1
How are the minority groups covered in British news media a. They are scarcely covered in any news media. b. They are widely covered in all kinds of news media. c. They are covered only in some special programs and tabloids. d. They are covered only in some mainstream TV programs and big newspapers.