Easy MCQ +4 / -1 PYQ · JEE Mains 2021

Let R = {(P, Q) | P and Q are at the same distance from the origin} be a relation, then the equivalence class of (1, $-$1) is the set :

  1. A $S = \{ (x,y)|{x^2} + {y^2} = \sqrt 2 \}$
  2. B $S = \{ (x,y)|{x^2} + {y^2} = 2\}$ Correct answer
  3. C $S = \{ (x,y)|{x^2} + {y^2} = 1\}$
  4. D $S = \{ (x,y)|{x^2} + {y^2} = 4\}$

Solution

Given R = {(P, Q) | P and Q are at the same distance from the origin}.<br><br>Then equivalence class of (1, $-$1) will contain al such points which lies on circumference of the circle of centre at origin and passing through point (1, $-$1).<br><br>i.e., radius of circle = $\sqrt {{1^2} + {1^2}} = \sqrt 2$<br><br>$\therefore$ Required equivalence class of (S)<br><br>$= \{ (x,y)|{x^2} + {y^2} = 2\}$.

About this question

Subject: Mathematics · Chapter: Sets, Relations and Functions · Topic: Sets and Operations

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