Surface area of a sphere: S=πd2
STitan=πd2Titan
SRhea=πd2Rhea
STitanSRhea=⧸πd2Titan⧸πd2Rhea=343
d2Titand2Rhea=343
d2Titan=d2Rhea∗(343)
dTitan=dRhea∗√(343)|dRhea=1530km
dTitan=1530km∗√(343)=1530km∗3.36650164612=5150.75km≈5151km
Diameter of Titan is 5151 km