1ˆ
ˆ
n
= −n Fig 10 24
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VECTOR ALGEBRA
451
Hence
a b
×
r
r
 =
ˆ
|
||
a b|sin
n
 
r
r
=
1ˆ
|
||
a b|sin
n
−
θ
r
r
b
a
= −
r×
r
7 In view of the Observations 4 and 6, we have
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
ˆ
,
 and