Question

The point
(1,2) is one extremity of
focal chord of
Parabola


y^2=
4x. the
length of this
focal
chord is.
options 2 4 6​

Answer 1

Answer:

Parabola: y

2

=4x............(1) (a=1)

The point (1,2) is end of focal chord, As focal chord passes through focus, the focal chord must pass through (1,0)

So, line passing through (1,2) and (1,0),

=>(y−0)=

1−1

2−0

(x−1)

=>x=1.............(2)

Line (2) is perpendicular to axis of parabola and passes through focus=> line (2) is LR and

length of LR=4(a)=4(1)

=4.