JEE Main202116 Mar 2021Evening ShiftMathematicsThree Dimensional GeometryActual
If the foot of the perpendicular from point 4 , 3 , 8 on the line L 1 : x - a l = y - 2 3 = z - b 4 , l ≠ 0 is 3 , 5 , 7 , then the shortest distance between the line L 1 and line L 2 : x - 2 3 = y - 4 4 = z - 5 5 is equal to
Options
- A1 2
- B1 6
- C2 3
- D1 3
Correct answer
B. 1 6
Step-by-step solution
3 , 5 , 7 satisfy the line L 1 3 - a ℓ = 5 - 2 3 = 7 - b 4 3 - a ℓ = 1   &   7 - b 4 = 1 a + ℓ = 3   … 1   &   b = 3   . . . 2 v → 1 = 4 , 3 , 8 - 3 , 5 , 7 v → 1 = 1 , - 2 , 1 v → 2 = ℓ , 3 , 4 v → 1 · v → 2 = 0 ⇒ ℓ - 6 + 4 = 0 ⇒ ℓ = 2 a + ℓ = 3 ⇒ a = 1 L 1 : x - 1 2 = y - 2 3 = z - 3 4 L 2 : x - 2 3 = y - 4 4 = z - 5 5 A = 1 , 2 , 3 B = 2 , 4 , 5 A B → = 1 , 2 , 2 p U