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1.Relation and Function
medium
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
A
$S =\left\{( x , y ) \mid x ^{2}+ y ^{2}=4\right\}$
B
$S =\left\{( x , y ) \mid x ^{2}+ y ^{2}=1\right\}$
C
$S =\left\{( x , y ) \mid x ^{2}+ y ^{2}=\sqrt{2}\right\}$
D
$S=\left\{(x, y) \mid x^{2}+y^{2}=2\right\}$
(JEE MAIN-2021)
Solution
Equivalence class of $(1,-1)$ is a circle with centre
at $(0,0)$ and radius $=\sqrt{2}$
$\Rightarrow x^{2}+y^{2}=2$
$S=\left\{(x, y) \mid x^{2}+y^{2}=2\right\}$
Standard 12
Mathematics
