问题
填空题
已知平面上三点A、B、C满足|
|
答案
∵|
|=6，|AB
|=8，|BC
|=10，CA
∴|
|2+|AB
|2=|BC
|2，∴∠B=90°，CA
∴
•AB
+BC
•BC
+CA
•CA
=AB
•(CA
+BC
)AB
=
•CA
=-AC
2=-100CA
故答案为：-100
搜题请搜索小程序“爱下问搜题”
已知平面上三点A、B、C满足|
|
∵|
|=6，|AB
|=8，|BC
|=10，CA
∴|
|2+|AB
|2=|BC
|2，∴∠B=90°，CA
∴
•AB
+BC
•BC
+CA
•CA
=AB
•(CA
+BC
)AB
=
•CA
=-AC
2=-100CA
故答案为：-100