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MHT CET202016 Oct 2020Morning ShiftMathematicsThree Dimensional GeometryActual

The direction cosines of a line which is perpendicular to lines whose direction ratit 3,-2,4 and 1,3,-2 are

Options

  1. A-8 285 , -10 285 , 11 285
  2. B-8 285 , 10 285 , 11 285
  3. C8 285 , 10 285 , 11 285
  4. D4 297 , 5 297 , 16 297

Correct answer

B. -8 285 , 10 285 , 11 285

Step-by-step solution

111.(B) Let a =3 i -2 j +4 k and b =1 i +3 j -2 k aligned a b &= | array ccc i & j & k 3 & -2 & 4 1 & 3 & -2 array | a b &=(4-12) i -(-6-4) j +(9+2) k &=-8 i +10 j +11 k | a b | &= (-8)²+(10)²+(11)² = 285 aligned Direction cosines are : -8 285 , 10 285 , 11 285

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