If the focus of a parabola is $(0,-3)$ and its directrix is $y=3$, then it equation is

If the focus of a parabola is $(0,-3)$ and its directrix is $y=3$, then it equation is
  1. $x^2=12 y$
  2. $y^2=-12 x$
  3. $y^2=12 x$
  4. $x^2=-12 y$

Solution


This is of the form of $x^2=-4 a y$ Here, $S \equiv(0,-a) \equiv(0,-3)$ Thus, $a=3$ $\therefore$ Equation of parabola is $x^2=-4 \times 3 y$ $\Rightarrow \quad x^2=-12 y$

Asked in: AP EAMCET 2022 (08 Jul Shift 2)

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