7.

(a) Let a :S band c:s d be real numbers. Sketch a graph of the rectangle

[a,b] x [c,d]:= {(x,y): x E [a,bJ,y E [c,d]}, and decide whether this set is connected. Explain your answers.

(b) Sketch a graph of the set Bl(-2,0) U Bl(2,0) U {(x,O): -1 < x < I}, and decide whether this set is connected. Explain your answers.