I. Given: AB = BCWe can only say that ΔABC is isosceles. It may or may not be equilateral as there is no information about side CA.II. Given: ∠ABC = 600
II alone is not sufficient as one angle alone cannot completely specify atriangle.I&II. ∠ABC = 60°⇒ ∠BAC + ∠ACB = 180°– 60° = 120°Given: AB = BC,⇒∠BAC = ∠ACB = 60°Hence, ΔABC is equilateral.∴ Ι&ΙΙ together are sufficient.