find unit vector perpendicular to A =2 i +j + k and B = i-j+2k.
The vector perpendicular to the two vectors would be given by the cross product of the two
now, let
A = 2i + j + k
B = i - j + 2k
and
C = A X B
thus,
C = (2i + j + k) X (i - j + 2k)
or
C = i(2+1) - j(4-1) + k(-2-1)
or
C = 3i - 3j - 3k
now, the unit vector would be
C = C / |C| = (3i - 3j - 3k) / [32 + 32 + 32]
or
C = (3i - 3j - 3k) / √[27]
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thus, the unit vector will be
C = (i - j - k) / √3