问题
填空题
在△ABC中，M是BC中点，AM=1，点P在AM上且满足
|
答案
∵AM=1，点P在AM上且满足
=-3PA
，∴|PM
|=PM
|1 4
|=AM
．1 4
∵
+PB
=2PC
，∴PM
•（PA
+PB
）=PC
•2PA
=-6PM
2=-6×(PM
)2=-1 4
．3 8
故答案为-
．3 8
搜题请搜索小程序“爱下问搜题”
在△ABC中，M是BC中点，AM=1，点P在AM上且满足
|
∵AM=1，点P在AM上且满足
=-3PA
，∴|PM
|=PM
|1 4
|=AM
．1 4
∵
+PB
=2PC
，∴PM
•（PA
+PB
）=PC
•2PA
=-6PM
2=-6×(PM
)2=-1 4
．3 8
故答案为-
．3 8