NTA Abhyas JEE Main2020MathematicsParabolaPractice
If two parabolas y 2 = 4 a x - k and x 2 = 4 a y - k have only one common point P, then the coordinates of P are
Options
- A2 k , 2 k
- Bk , k
- Ca , 2 k
- Dk , 2 a
Correct answer
A. 2 k , 2 k
Step-by-step solution
Parabolas y 2 = 4 a x - k and x 2 = 4 a y - k touch each other at the line y = x ( ∵ both parabolas are inverse of each other) ⇒ y = x is the common tangent at P ⇒ we get point P by solving y 2 = 4 a x - k and y = x ⇒ point of contact P = 2 a , 2 a ⇒ 2 a 2 = 4 a 2 a - k ⇒ k = a ⇒ P = 2 k , 2 k