问题 选择题
已知O为坐标原点,
OA
=(-3,1),
OB
=(0,5),且
AC
OA
BC
AB
,则点C的坐标为(  )
A.(-3,-
29
4
B.(3,
29
4
C.(-3,
29
4
D.(3,-
29
4
答案

设C(x,y)则

AC
=
OC
-
OA
=(x+3,y-1);  
BC
=
OC
-
OB
=(x,y-5)
AB
=
OB
-
OA
=(3,4)

AC
OA
BC
AB

-3(y-1)=x+3
3x+4(y-5)=0

解得

x=-3
y=
29
4

故选C

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