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Question
Select the correct option from the given alternatives:
If the focus of the parabola is (0, –3) its directrix is y = 3 then its equation is
Options
x2 = – 12y
x2 = 12y
y2 = 12x
y2 = −12x
Solution
x2 = – 12y
Explanation;
SP2 = PM2
∴ (x – 0)2 + (y + 3)2 = `|(y - 3)/sqrt(1)|^2`
∴ x2 + y2 + 6y + 9 = y2 – 6y + 9
∴ x2 = – 12y
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