6 1  Scalar (or dot) product of two vectors
Definition 2 The scalar product of two nonzero vectors 
aand
rb
r
, denoted by a b
⋅
r
r
, is
Fig 10 18
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 MATHEMATICS
442
defined as
a b
⋅
r
r
 = |
| |
| cos ,
a
b
θ
r
r
where, θ is the angle between 
and
, 0
a
b
   
r
r
 (Fig 10 19)