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COMEDK2016MathematicsVector Algebra

If a and b are the two vectors such that | a |=3 3 ,|b|=4 and | a + b |= 7 , the angle between a and b is

Options

  1. A150^
  2. B30^
  3. C60^
  4. D120^

Correct answer

A. 150^

Step-by-step solution

We have, |a|=3 3 ,|b|=4 and | a +b|= 7 Now, | a + b |²=| a |²+| b |²+2| a || b | ( 7 )²=(3 3 )²+16+2(3 3 )(4) 7=27+16+24 3 24 3 =-36 =- 36 24 3 =- 3 2 =150^

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