Question

If $A=\left\{\right(x,y):x^2+y^2\le 1;x,yϵR\}$ and $B=\left\{\right(x,y):x^2+y^2\ge 4;x,yϵR\}$, then

• A. $A-B=\varphi$
• B. $B-A=\varphi$
• C. $A\cap B\ne \varphi$
• D. $A\cap B=\varphi$

Answer 1

The correct option is D $A\cap B=\varphi$

$A$ is the set of all points on the inner circle $x^2+y^2=1.B$ is the set of all points on the outer circle $x^2+y^2=4$.
$\therefore A-B=A,B-A=B,A\cap B=\varphi$.