设a的起点为A(2,4),终点为B(-2,1),写出a的坐标,求出与a同向的单位向量a2

2025-05-21 04:56:25
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回答(1):

a = AB = OB-OA= (-4,-3)

|a|= ((-3)^2+(-4)^2)^(1/2) =5
a2 = a/|a| = (-4/5,-3/5)