Write the value of 
where 
is any vector.
Let 
(1)
(2)
(3)
Put the values obtained in the given equation
We get:
=
i.e.
= 
1
Write the value of where is any vector.
Let
(1)
(2)
(3)
Put the values obtained in the given equation
We get:
=
i.e.
=