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** = 2**i** + **j** +** k**

**B** =** i** - **j** + 2**k**

and

**C** = A X B

thus,

**C** = (2**i** + **j** + **k**) X (**i** - **j** + 2**k**)

or

**C** = **i**(2+1) - **j**(4-1) + **k**(-2-1)

or

**C** = 3**i** - 3**j** - 3**k**

now, the unit vector would be

*C *= **C **/ |C| = (3**i** - 3**j** - 3**k**) / [3^{2} + 3^{2} + 3^{2}]

or

*C* = (3**i** - 3**j** - 3**k**) / √[27]

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thus, the unit vector will be

*C *= (**i** - **j** - **k**) / √3

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