The given equation is x2 = -9y
Here, the coefficient of y is negative.
Hence, the parabola open downwards.
On comparing this equation with x2 = -4ay, we get,
-4a = -9
⇒ a =
Co-ordinates of the focus = (0,-a) =
Since, the given equation involves x2, the axis of the parabola is the y-axis.
Equation of directrix, y = a, then,
Length of latus rectum = 4a = 9
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