Equation of parabola : y2 = -16x
On comparing with : y2 = -4ax , 4a = 16 , a = 4
Focus : S = (-a,0) = (-4,0)
Equation of directrix :
x - a = 0
∴ x - 4 = 0
Length of latus recturm = 4a = 16 units
Ends of latus rectum :
L = (a , 2a) = (-4,8)
L’= (-a,-2a) = (-4,-8)