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Manipal MET2018MathematicsThree Dimensional Geometry

If ( 1 2 , 1 3 , n ) are the direction cosines of a line, then the value of n is

Options

  1. A23 6
  2. B23 36
  3. C2 3
  4. D3 2

Correct answer

A. 23 6

Step-by-step solution

Since, ( 1 2 , 1 3 , n ) are the direction cosines of a line, then ( 1 2 )^2+ ( 1 3 )^2+n^2=1 1 4 + 1 9 +n^2=1 n^2=1- 1 4 - 1 9 = 23 36 n= 23 6

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