If the focus of a parabola is (0,-3) and its directrix is y=3, then its equation isA. `x^(2)=-12y`B. `x^(2)=12y`C. `y^(2)=-12x`D. `y^(2)=12x`

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

1.	If the focus of a parabola is (0,-3) and its directrix is y=3, then its equation isA. `x^(2)=-12y`B. `x^(2)=12y`C. `y^(2)=-12x`D. `y^(2)=12x`
Answer» Correct Answer - A Given that, focus of parabola at F (0,-3) and equation of directrix is y=3 Let any point on the parabola is P (x,y). Then, PF=`abs(y-3)` `rArr sqrt((x-0)^(2)+(y-3)^(2))=abs(y-3)` `rArrx^(2)+y^(2)+6y+9=y^(2)-6y+9` `rArrx^(2)+12y=0` `rArrx^(2)=-12y`

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