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Class 12 Three Dimensional Geometry · Very Long Answer5 Marksshortest_distance

Class 12 Maths · Three Dimensional Geometry · Very Long Answer #90

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

✅ Step-by-Step Solution

Final Answer: sqrt(265)/265
  1. For nonparallel lines use D=|(B−A)·(d×e)|/|d×e|.
  2. B−A=(1,2,2), d×e=(-15,2,6).
  3. The numerator is 1 and the denominator is sqrt(265).
  4. Distance is nonnegative; take the nonnegative square root after simplifying.
  5. Therefore D=sqrt(265)/265.

📋 CBSE Stepwise Marking Scheme

  • [1 mark] For nonparallel lines use D=|(B−A)·(d×e)|/|d×e|.
  • [1 mark] B−A=(1,2,2), d×e=(-15,2,6).
  • [1 mark] The numerator is 1 and the denominator is sqrt(265).
  • [1 mark] Distance is nonnegative; take the nonnegative square root after simplifying.
  • [1 mark] Therefore D=sqrt(265)/265.

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