问题 选择题
已知点P为△ABC内一点,且
PA
+2
PB
+3
PC
=
0
,则△APB,△APC,△BPC的面积之比等于(  )
A.9:4:1B.1:4:9C.3:2:1D.1:2:3
答案

PA
+2
PB
+3
PC
=
0
,∴
PA
+
PC
=-2
(PB
+
PC
),如图:

PA
+
PC
=
PD
=2
PF
PB
+
PC
=
PE
=2
PG

PF
=2
PG

∴F、P、G三点共线,且PF=2PG,GF为三角形ABC的中位线

S△APC
S△BPC
=
1
2
×PC ×h1
1
2
×PC ×h2
=
h1
h2
=
PF
PG
=2

而S△APB=

1
2
S△ABC

∴△APB,△APC,△BPC的面积之比等于3:2:1

故选 C

选择题
问答题 简答题