AP EAMCET201921 Apr 2019Evening ShiftMathematicsParabolaActual
The normal at a point on the parabola y 2 = 4 x passes through ( 5 , 0 ) . If two more normals to this parabola also pass through ( 5 , 0 ) , then the centroid of the triangle formed by the feet of these three normals is
Options
- A1 2 , 1 2
- B( 2 , 0 )
- C( 5 , 0 )
- D( 0 , 2 )
Correct answer
B. ( 2 , 0 )
Step-by-step solution
The given equation of a parabola, y 2 = 4 x The equation of normal at a point P ( 5 , 0 ) y = - t x + 2 t + t 3 0 = - 5 t + 2 t + t 3 3 t = t 3 t 2 = 3 t = ± 3 , 0 Here, a = 1 Co-normal point P a t 1 2 , 2 a t 1 = ( 3 , 2 3 ) Q a t 2 2 , 2 a t 2 = ( 3 , - 2 3 ) R a t 3 2 , 2 a t 3 = ( 0 , 0 ) The centroid is, C = 3 + 3 + 0 3 , 2 3 - 2 3 + 0 3 C = 6 3 , 0 = 2 , 0