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AP EAMCET20225 Jul 2022Evening ShiftMathematicsVector AlgebraActual

Three vectors a , b , c satisfy the condition a + b + c = 0 . If | a |=1,| b |=3,| c |=4 then a b + b c + c a =

Options

  1. A12
  2. B-12
  3. C-13
  4. D13

Correct answer

C. -13

Step-by-step solution

( a + b + c )^2=| a |^2+| b |^2+| c |^2+2( a b + b c + c a ) aligned & 0=(1)^2+(3)^2+(4)^2+2( a b + b c + c a ) & 2( a b + b c + c a )=-26 & a b + b c + c a =-13 aligned

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