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Mathematics
Mathematics
Problem
a
,
b
,
c
\mathbf{a}, \mathbf{b}, \mathbf{c}
a
,
b
,
c
are three vectors, such that
a
+
b
+
c
=
0
\mathbf{a} + \mathbf{b} + \mathbf{c} = \mathbf{0}
a
+
b
+
c
=
0
,
∣
a
∣
=
1
|\mathbf{a}| = 1
∣
a
∣
=
1
,
∣
b
∣
=
2
|\mathbf{b}| = 2
∣
b
∣
=
2
,
∣
c
∣
=
3
|\mathbf{c}| = 3
∣
c
∣
=
3
, then
a
⋅
b
+
b
⋅
c
+
c
⋅
a
\mathbf{a} \cdot \mathbf{b} + \mathbf{b} \cdot \mathbf{c} + \mathbf{c} \cdot \mathbf{a}
a
⋅
b
+
b
⋅
c
+
c
⋅
a
is equal to a. 0 b. -7 c. 7 d. 1
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