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MHT CET202314 May 2023Morning ShiftMathematicsVector AlgebraActual

If a , b , c are unit vectors and is angle between a and c and a +2 b +2 c = 0 , then | a c |=

Options

  1. A15 2
  2. B15 4
  3. C15
  4. D15 3

Correct answer

B. 15 4

Step-by-step solution

aligned & a +2 b +2 c = 0 & a +2 c =-2 b aligned Squaring on both sides, we get aligned & | a |^2+4 a c +4| c |^2=4| b |^2 & 1+4| a || c | +4=4 & =- 1 4 & = 15 4 & | a c |=| a || c | & =(1)(1) ( 15 4 )= 15 4 aligned

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