The angle between the lines with direction ratios 2 , - 2 , 1 and 1 , - 2 , 2 is

The angle between the lines with direction ratios 2,-2,1 and 1,-2,2 is
  1. cos-149
  2. cos-189
  3. π6
  4. π2

Solution

Direction ratios are (2,-2,1) and (1,-2,2)

cosθ=2×1+(-2×-2)+1×222+(-2)2+12 12+(-2)2+22

=83×3=89

Asked in: AP EAMCET 2020 (23 Sep Shift 1)

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