If the equation of the parabola, whose vertex is at and the directrix is , is then
is equal to
is equal to
- (A)575
- (B)-575
- (C)576
- (D)-576✓ Correct
Answer: (D)
Solution
The vertex is and directrix is . The focus lies on the perpendicular from the vertex to the directrix.
The foot of perpendicular from to the directrix:
So the foot is at . The focus is at (reflection of vertex about foot).
The parabola equation is: distance from point to focus = distance from point to directrix.
Expanding and simplifying:
Comparing:
Answer: (D)
The foot of perpendicular from to the directrix:
So the foot is at . The focus is at (reflection of vertex about foot).
The parabola equation is: distance from point to focus = distance from point to directrix.
Expanding and simplifying:
Comparing:
Answer: (D)

JEE Main · 2022 · 27 Jun 2022 · Shift 2 · Single correct option