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If AFB is a focal chord of the parabola ...

If AFB is a focal chord of the parabola `y^(2) = 4ax` such that `AF = 4` and `FB = 5` then the latus-rectum of the parabola is equal to (a) 80 (b)`9/80` (c) 9 (d) `80/9`

A

80

B

`(9)/(80)`

C

9

D

`(80)/(9)`

Text Solution

Verified by Experts

The correct Answer is:
D
`FA = 4` and `FB = 5`
We know that `(1)/(a) = (1)/(AF) + (1)/(FB)`
`rArr a = (20)/(9) rArr 4a =(80)/(9)`
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