> 数学 >
△ABC中.AB边的高为CD,若
CB
=
a
CA
=
b
a
b
=0,|
a
|=1,|
b
|=2,请用
a
b
表示
AD
人气:220 ℃ 时间:2019-11-13 05:59:56
解答
如图所示,
a
b
=0,∴
a
b

又|
a
|=1,|
b
|=2,
∴|
AB
|=
12+22
=
5
,|
AD
|=
|
AC
|2
|
AB
|
=
4
5
5

AD
4
5
AB
=
4
5
(
a
b
).
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