UPSC NDA Math Model Paper 4

Here, we have to find the equation of the parabola whose focus is at F(0, - 3) and directrix y = 3.
As we know that, parabola of the form x2=−4ay has focus at (0, - a) and equation of directrix is given by y = a.
So, by comparing the focus F(0, - 3) and directrix y = 3 with (0, - a) and y = a respectively we get
⇒a=3
So, the equation of the required parabola is x2=−4⋅3⋅y=−12y
Hence, option C is the correct answer.