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COMEDK2012MathematicsThree Dimensional Geometry

The direction cosines of the vector 2 i + j -2 k is equal to

Options

  1. A2 3 , 1 3 ,- 2 3
  2. B2 3 , 1 3 , 2 3
  3. C1 3 , 2 3 ,- 2 3
  4. D2 3 , 2 3 , 1 3

Correct answer

A. 2 3 , 1 3 ,- 2 3

Step-by-step solution

Let a =2 i + j -2 k So, | a |= 4+1+4 = 9 =3 So, direction cosines of vector are 2 3 , 1 3 ,- 2 3 .

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