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JEE Main20244 Apr 2024Evening ShiftMathematicsVector AlgebraActual

For >0 , let be the angle between the vectors a = i + j -3 k and b =3 i - j +2 k . If the vectors a + b and a - b are mutually perpendicular, then the value of (14 cos )^2 is equal to

Options

  1. A50
  2. B40
  3. C25
  4. D20

Correct answer

C. 25

Step-by-step solution

aligned & ( a + b ) ( a - b )=0, >0 & | a |^2-| b |^2=0 1+ ^2+9=9+1+4 & =2, = a - b | a | | b | = 3- -6 14 14 & 14 =3-8=-5 & (14 )^2=25 aligned

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