JEE Main202325 Jan 2023Evening ShiftMathematicsParabolaActual
The equations of two sides of a variable triangle are x = 0 and y = 3 , and its third side is a tangent to the parabola y 2 = 6 x . The locus of its circumcentre is :
Options
- A4 y 2 - 18 y - 3 x - 18 = 0
- B4 y 2 + 18 y + 3 x + 18 = 0
- C4 y 2 - 18 y + 3 x + 18 = 0
- D4 y 2 - 18 y - 3 x + 18 = 0
Correct answer
C. 4 y 2 - 18 y + 3 x + 18 = 0
Step-by-step solution
Given, Equation of parabola is y 2 = 6 x , Also the general equation of a parabola is y 2 = 4 a x On comparing, we get ⇒ 4 a = 6 ⇒ a = 3 2 Tangent on parabola y 2 = 4 a x is given by y = m x + a m , So, y = m x + 3 2   m ;   ( m ≠ 0 ) Now using the midpoint formula we get, h = 6   m - 3 4   m 2 ,   k = 6   m + 3 4   m Now, eliminating m and we get 3 h = 2 - 2 k 2 + 9 k - 9 ⇒ 3 h = - 4 k 2 + 18 k - 18 ⇒ 4 k 2 - 18 k + 3 h + 18 = 0 ∴ The locus of