Example 27 - If i+j+k, 2i+5j, 3i+2j-3k and i-6j-k are position - Collinearity Of two vectors

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Slide68.JPG

  1. Chapter 10 Class 12 Vector Algebra
  2. Serial order wise
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Example 27 If + + , 2 + 5 , 3 + 2 3 and 6 are the position vectors of points A, B, C and D respectively, then find the angle between and . Deduce that and are collinear. Angle between & is given by cos = . Now, cos = . = + 4 . 2 8 + 2 3 2 6 2 = 1 2 + 4 8 1(2) 3 2 6 2 = 2 32 2 3 6 2 2 = 36 36 = 1 Since cos = 1, = 180 So, = 180 = 180 = So, angle between & is Also, Since angle between & is 180 , they are in opposite directions Since & are parallel to the same line , they are collinear.

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