[7 points] Let {Cr : r ∈ [0,∞)} be the family of indexed sets given by Cr = {(x, y) ∈ R 2 : x 2 + y 2 = r}. a. Describe

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[7 points] Let {Cr : r ∈ [0,∞)} be the family of indexed sets
given by Cr = {(x, y) ∈ R 2 : x 2 + y 2 = r}.
a. Describe each of the sets Cr geometrically.
b. Prove that S r∈[0,∞) Cr = R 2 .
= 7. [7 points) Let {Cr: 1 € [0,00)} be the family of indexed sets given by CH = {(x,y) € R2 : x2 + y2 =r} a. Describe each of the sets C, geometrically. b. Prove that U C. =R2. TE[0,00)