JEE Advanced2013MathematicsThree Dimensional GeometryActual
Perpendiculars are drawn from points on the line x + 2 2 = y + 1 - 1 = z 3 to the plane x + y + z = 3 . The feet of perpendiculars lie on the line
Options
- Ax 5 = y - 1 8 = z - 2 - 1 3
- Bx 2 = y - 1 3 = z - 2 - 5
- Cx 4 = y - 1 3 = z - 2 - 7
- Dx 2 = y - 1 - 7 = z - 2 5
Correct answer
D. x 2 = y - 1 - 7 = z - 2 5
Step-by-step solution
The equation od given line is x + 2 2 = y + 1 - 1 = z 3 = λ Now any two points on this line are A - 2 , - 1 , 0 ,B 0 , - 2 , 3 for λ = 0 ,  1 Let foot of perpendicular from A ( - 2 , - 1 , 0 ) on plane is α ,  β ,  γ ⇒ α + 2 1 = β + 1 1 = γ - 0 1 = μ say Also the point lies on the plane, hence α + β + γ = 3 ⇒ μ - 2 + μ - 1 + μ = 3 ⇒ μ = 2 Hence the coordinates of M are ⇒ M 0, 1, 2 Similarly foot of