(31) |

Note that we have two ways of specifying the vector displacement of point from
the origin: we can either write or
. The
expression
is interpreted as follows: starting at the origin,
move along vector in the direction of the arrow, then move along
vector in the *opposite* direction to the arrow. In other words,
a *minus* sign in front of a vector indicates that we should move along that vector in
the *opposite* direction to its arrow.

Suppose that the components of vectors and are
and
, respectively. As is easily demonstrated,
the components of the
resultant vector
are

(32) | |||

(33) | |||

(34) |

In other words, the components of the sum of two vectors are simply the algebraic sums of the components of the individual vectors.