Dot product
In linear algebra, the dot product of two vectors is defined to be
. The dot product is bilinear.
For two vectors and
, we also have
, where
is the angle that
and
form with each other. In particular, for nonzero vectors
and
, we have
if and only if
and
are perpendicular, and
if and only if
and
are parallel, from which the identity
follows.
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