Having trouble with this one.

(a) Let C = {((x, y), z) ( R2 x R, x2 + 22 =1}. For each of the following sets Gi with i E {1, 2, 3} . G1 = Cn ((R+) 2 x IR) . G2 = Cn ( R2 x R+) . G3 = Cn ((R+) 2 x R+ ) indicate if it is the Graph of a function fi : Di -> R with domain D; C R2. If it is the case, give the domain and the range of the function and indicate if it is injective, surjective or bijective. Prove your claims