Here, x, y and z are called
as the scalar components of rr , and 
ˆ
ˆ
ˆ
,
  and
xi
yj
zk  are called the vector components
of rr along the respective axes Sometimes x, y and z are also termed as rectangular
components The length of any vector 
ˆ
ˆ
ˆ
r
xi
yj
zk
=
+
+
r
, is readily determined by applying the
Pythagoras theorem twice We note that in the right angle triangle OQP1 (Fig 10