问题 填空题
在△ABC中,点D满足
AD
=3
DC
BD
BA
CB
(λ,μ∈R),则λ•μ=______.
答案

∵点D满足

AD
=3
DC

AD
=
3
4
AC

AC
=
BC
-
BA

AD
=
3
4
(
BC
-
BA
),

BD
=
BA
+
AD
=
BA
+
3
4
(
BC
-
BA
)
=
1
4
BA
-
3
4
CB

BD
BA
CB

λ=

1
4
μ=
3
4

λμ=

1
4
×
3
4
=
3
16

故答案为:

3
16

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