Question:
Let $R=\{(P, Q) \mid P$ and $Q$ are at the same distance from the origin $\}$ be a relation, then the equivalence class of $(1,-1)$ is the set:
Correct Option: , 4
Solution:
Equivalence class of $(1,-1)$ is a circle with centre
at $(0,0)$ and radius $=\sqrt{2}$
$\Rightarrow x^{2}+y^{2}=2$
$S=\left\{(x, y) \mid x^{2}+y^{2}=2\right\}$