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Two unit vectors ' a ₁ 'and ' a ₂ ' are inclined to each other at an angle ' '. If | a ₁- a ₂ |= 3 , then the value of ( a ₁- a ₂ ) (2 a ₁- a ₂ ) is

Options

  1. A1 2
  2. B2
  3. C1
  4. D3 2

Correct answer

D. 3 2

Step-by-step solution

| a ₁- a ₂ |= 3 (1) | a ₁ |= | a ₂ |=1 a ₁²+ a ₂²-2 a ₁ a ₂ =3 squaring (1) 1+1-2 =3 = ( a ₁- a ₂ ) (2 a ₁- a ₂ ) =-1 / 2

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