Easy MCQ +4 / -1 PYQ · JEE Mains 2022

If the length of the latus rectum of a parabola, whose focus is $(a, a)$ and the tangent at its vertex is $x+y=a$, is 16, then $|a|$ is equal to :

  1. A $2 \sqrt{2}$
  2. B $2 \sqrt{3}$
  3. C $4 \sqrt{2}$ Correct answer
  4. D 4

Solution

<p>Equation of tangent at vertex : $L \equiv x + y - a = 0$</p> <p>Focus : $F \equiv (a,a)$</p> <p>Perpendicular distance of L from F</p> <p>$$ = \left| {{{a + a - a} \over {\sqrt 2 }}} \right| = \left| {{a \over {\sqrt 2 }}} \right|$$</p> <p>Length of latus rectum $= 4\left| {{a \over {\sqrt 2 }}} \right|$</p> <p>Given $4\,.\,\left| {{a \over {\sqrt 2 }}} \right| = 16$</p> <p>$\Rightarrow |a| = 4\sqrt 2$</p>

About this question

Subject: Mathematics · Chapter: Conic Sections · Topic: Parabola

This question is part of PrepWiser's free JEE Main question bank. 146 more solved questions on Conic Sections are available — start with the harder ones if your accuracy is >70%.

Drill 25 more like these. Every day. Free.

PrepWiser turns these solved questions into a daily practice loop. Chapter-wise drills, full mocks, AI doubt chat. No auto-renew.

Start free →