Graphics Reference
In-Depth Information
come to apply these techniques to real vectors, we will discover that some directions are more
convenient than others.
Defining a line segment using
−
AB or
−
−
BA is a useful notation we shall continue to employ.
However, we can also give names to line segments, such as
a
n
,or
q
. Note that the boldface
type differentiates a vector's name from the more familiar names given to scalar quantities such
as x y,ort. This is a widely accepted notation for referencing vectors and enables us to create
diagrams such as the one shown in Fig. 1.6.
n
t
s
m
r
Figure 1.6.
From Fig. 1.6 we can make the following observations:
=
+
r
s
t
s
=
m
−
n
and
t
=
n
−
m
+
r
One problem-solving strategy we use later on creates a chain of indirect vectors that eventually
reveals the vector on the direct route. Such a situation is shown in Fig. 1.7, which permits us
to write
p
=
r
+
s
+
t
−
n
s
t
n
r
p
Figure 1.7.
You may be wondering why the vector
n
is reversed in Fig. 1.7. Why isn't it pointing in the
same direction as
r
s
, and
t
? Well, when we come to labeling our vectors, certain directions
are more convenient than others, which gives rise to such conflicts. However, it is nothing to
worry about, because a simple minus sign resolves the problem.
