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AP EAMCET201920 Apr 2019Evening ShiftMathematicsThree Dimensional GeometryActual

Let a and b be unit vectors with as the acute angle between them. If 1 2 | a - b |= , then 4 ^2=

Options

  1. A4
  2. B1
  3. C3
  4. D2

Correct answer

B. 1

Step-by-step solution

It is given, that 1 2 | a - b |= ( ) On squaring both sides, we get aligned & | a |^2+| b |^2-2| a || b | =4 ^2( ) & 1+1-2 =4 ^2( ) & 2(1- )=4 ^2( ) 4 ^2 ( 2 )=4 ^2( ) & = 1 2 [ (1- )=2 ^2 2 ] & 4 ^2=4 ( 1 2 )^2=1 aligned Hence, option (b) is correct.

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