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Mathematics
Mathematics
Problem
For a vector
a
\mathbf{a}
a
in
R
3
\mathbb{R}^3
R
3
, suppose
a
⋅
a
=
0
\mathbf{a}\cdot\mathbf{a}=0
a
⋅
a
=
0
. Which one of the following must be true? a)
∣
a
∣
=
1
|\mathbf{a}|=1
∣
a
∣
=
1
b) At least one component of
a
\mathbf{a}
a
equals
0
0
0
c)
a
=
0
\mathbf{a}=\mathbf{0}
a
=
0
d)
a
\mathbf{a}
a
is perpendicular to itself but
a
≠
0
\mathbf{a}\neq\mathbf{0}
a
=
0
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