Let 
and 
. Find a vector 
which is perpendicular to both 
a and 
, and 
Given: 
Let 
Because 
is perpendicular to both 
and 
.
Then 
And 
And 
(given)
After solving (1), (2) and (3) we get:
Hence 
Hence, the required vector is 
12
Let and . Find a vector which is perpendicular to both a and , and
Given:
Let
Because is perpendicular to both and .
Then
And
And (given)
After solving (1), (2) and (3) we get:
Hence
Hence, the required vector is