Dot
Product
In two dimensions, (ai +
bj)•(ci + dj)
= ac + bd. In three
dimensions,
(ai + bj + ck)•(di +
ej + fk)
= ad
+ be + cf.
In either case, u • v = u v cos θ,
where θ is the angle between
the vectors.
See also
Cross product, triple product, cosine
