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JEE Main 202131 AugustMorning Shift
Exam
JEE Main
Year
2021
Date
31 August
Shift
Morning Shift
Subject
Mathematics
Chapter
Parabola

JEE Main 2021 · 31 August · Morning Shift · Mathematics · Parabola

The length of the latus rectum of a parabola, whose vertex and...

The length of the latus rectum of a parabola, whose vertex and focus are on the positive xx-axis at a distance RR and S(>R)S ( > R ) respectively from the origin, is :

Options

  1. A2(S−R)2 ( S - R )
  2. B2(S+R)2 ( S + R )
  3. C4(S−R)4 ( S - R )
  4. D4(S+R)4 ( S + R )

Correct answer

C. 4(S−R)4 ( S - R )

Step-by-step solution

A parabola, whose vertex and focus are on the positive xx- axis at a distance RR and S(>R)S ( > R ) respectively from the origin.

y2=4a(x−R){y}^{2} = 4a ( x - R )
y2=4(S−R)(x−R){y}^{2} = 4 ( S - R ) ( x - R )
Length of Latus rectum=4(S−R)= 4 ( S - R )

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