问题 填空题
已知向量
a
=(cosα,sinα),
b
=(cos(α+
π
3
),sin(α+
π
3
))
|
a
-
b
|
=______.
答案

|

a
-
b
|2=(
a
-
b
)
2
=
a
2
-2
a
b
+
b
2

=2-2cosαcos(α+

π
3
+sinαsin(α+
π
3
)

=2-2cos[α-(α+

π
3
)]

2-2cos

π
3

=1

|

a
-
b
|=1

故答案为:1

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