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Mathematics
Mathematics
Problem
Suppose
A
A
A
is
(
1
,
2
,
3
)
(1, 2, 3)
(
1
,
2
,
3
)
,
B
B
B
is
(
2
,
5
,
k
)
(2, 5, k)
(
2
,
5
,
k
)
,
C
C
C
is
(
5
,
1
,
0
)
(5, 1, 0)
(
5
,
1
,
0
)
, and
B
A
C
^
=
60
∘
\widehat{BAC} = 60^\circ
B
A
C
=
6
0
∘
. Find
k
k
k
.
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