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Class 12 Three Dimensional Geometry · Long Answer3 Marksshortest_distance

Class 12 Maths · Three Dimensional Geometry · Long Answer #86

Find the shortest distance between r=(1,-2,3)+t(-1,1,-2), t∈ℝ and r=(1,-1,1)+t(1,2,2), t∈ℝ.

✅ Step-by-Step Solution

Final Answer: 2*sqrt(5)/5
  1. For nonparallel lines use D=|(B−A)·(d×e)|/|d×e|.
  2. B−A=(0,1,-2), d×e=(6,0,-3).
  3. The numerator is 6 and the denominator is 3*sqrt(5).
  4. Therefore D=2*sqrt(5)/5.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] For nonparallel lines use D=|(B−A)·(d×e)|/|d×e|.
  • [1 mark] B−A=(0,1,-2), d×e=(6,0,-3).
  • [1 mark] The numerator is 6 and the denominator is 3*sqrt(5).
  • [0.5 marks] Therefore D=2*sqrt(5)/5.

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