JEE Main202325 Jan 2023Evening ShiftMathematicsThree Dimensional GeometryActual
The foot of perpendicular of the point 2 , 0 , 5 on the line x + 1 2 = y - 1 5 = z + 1 - 1 is α , β , γ . Then. Which of the following is NOT correct?
Options
- Aα β γ = 4 15
- Bα β = - 8
- Cβ γ = - 5
- Dγ α = 5 8
Correct answer
C. β γ = - 5
Step-by-step solution
Given line is L : x + 1 2 = y - 1 5 = z + 1 - 1 = λ (let) Let foot of perpendicular is P 2 λ - 1 , 5 λ + 1 , - λ - 1 P A → = 3 - 2 λ i ^ - 5 λ + 1 j ^ + 6 + λ k ^ Direction ratio of line is b → = 2 i ^ + 5 j ^ - k ^ Now, P A → ⊥ L , so P A → · b → = 0 ⇒ 2 3 - 2 λ - 5 5 λ + 1 - 6 + λ = 0 ⇒ 6 - 4 λ - 25 λ - 5 - 6 - λ = 0 ⇒ - 30 λ - 5 = 0 ⇒ λ = - 1 6 So, P 2 λ - 1 , 5 λ