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AB垂直AC,向量BD=5/3向量BC,AC=2,求向量AC*向量AD
人气:267 ℃ 时间:2020-06-07 02:37:50
解答
AB垂直AC
=>AB.AC =0
AC.AD
= AC.(AB+BD)
=AC.AB + AC.BD
= 0 + AC.( (5/3)BC)
= (5/3) AC.( AC -AB )
= (5/3) |AC|^2
= 20/3
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