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Class 12 Three Dimensional Geometry · Long Answer3 Marksshortest_distance

Class 12 Maths · Three Dimensional Geometry · Long Answer #50

Find the shortest distance between r=(1,2,-4)+t(2,3,6), t∈ℝ and r=(3,3,-5)+t(4,6,12), t∈ℝ.

✅ Step-by-Step Solution

Final Answer: sqrt(293)/7
  1. The directions are proportional. Use D=|(B−A)×d|/|d|.
  2. B−A=(2,1,-1), (B−A)×d=(9,-14,4).
  3. The squared distance is 293/49.
  4. Therefore D=sqrt(293)/7.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] The directions are proportional. Use D=|(B−A)×d|/|d|.
  • [1 mark] B−A=(2,1,-1), (B−A)×d=(9,-14,4).
  • [1 mark] The squared distance is 293/49.
  • [0.5 marks] Therefore D=sqrt(293)/7.

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