Question

Find the coordinates of focus, equation of directrix and length of the latus rectum for $y^2=-8x$.

Answer 1

The given equation of parabola is $y^2=-8x$
which is of the form $y^2=-4ax.\therefore 4a=8\Rightarrow a=2$
Therefore, coordinates of focus are (-2,0)
Axis of parabola is y = 0
Equation of the directrix is
$x=2\Rightarrow x-2=0$
Length of latus rectum $=4\times 2=8$