In each of the following, find the coordinates of the focus, axis of the parabola, the equation of the directrix and the length of the latus rectum.
x2 = – 9y
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 = 
Thus,
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,
x = 
Length of latus rectum = 4a = 9
6