问题 选择题
设P是△ABC所在平面内的一点,
BC
+
BA
=2
BP
,则(  )
A.
PA
+
PB
=
0
B.
PC
+
PA
=
0
C.
PB
+
PC
=
0
D.
PA
+
PB
+
PC
=
0
答案

BC
+
BA
=2
BP

BC
-
BP
=
BP
-
BA

PC
=
AP

PC
-
AP
=
0

PC
+
PA
=
0

故选B.

解答题
单项选择题