find the focus length of the lotus rectum and directrix of the parabola y Square =11x About the author Melanie
Answer: Given y 2 =−12x Since the above equation is involving y 2 Its axis is x−axis Also coefficient of x is negative (-12) Hence we use equation y 2 =−4ax Comparing y 2 =−12x….(1) [Given] y 2 =−4ax From (1) and (2) −12x=−4ax 4ax=12x a=3 Coordinates of focus is (-a,0) i.e focus (−3,0) Equation of directix is x=a x=3 Latus rectum =4a =4×3 =12 Reply
Answer:
Given y
2
=−12x
Since the above equation is involving y
2
Its axis is x−axis
Also coefficient of x is negative (-12)
Hence we use equation
y
2
=−4ax
Comparing
y
2
=−12x….(1) [Given]
y
2
=−4ax
From (1) and (2)
−12x=−4ax
4ax=12x
a=3
Coordinates of focus is (-a,0)
i.e focus (−3,0)
Equation of directix is
x=a
x=3
Latus rectum =4a
=4×3
=12