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COMEDK2015MathematicsVector Algebra

Given, two vectors i - j and i -2 j . The unit vector, coplanar with the two given vectors and perpendicular to ( i - j ) is

Options

  1. A1 2 ( i + j )
  2. B1 5 (2 i + j )
  3. C1 2 ( i + j )
  4. DNone of these

Correct answer

C. 1 2 ( i + j )

Step-by-step solution

Let = i - j and b = i -2 j The required vector is along the vector a ( a b )=( a b ) a -( a a ) b aligned &=3( i - j )-2( i -2 j ) &=3 i -3 j -2 i +4 j = i + j aligned Hence, required vectors are given by ( i + j ) 1+1 = 1 2 ( i + j )

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