State the property that is used in each of the following statements?
(i) If a || b, then ∠1 = ∠5.
(ii) If ∠4 = ∠6, then a || b.
(iii) If ∠4 + ∠5 = 180°, then a || b.

(i): Given $\mathrm{a} \left|\right| \mathrm{b}$

Therefore $\angle1=\angle5$ (Pair of corresponding angles)

(ii): Given $\mathrm{\angle }4 =\mathrm{\angle }6$

Therefore $a\text{ || }b$ (If pair of alternate angles are equal, then the lines are parallel)

(iii): Given $\angle4+\angle5=180\degree$

Therefore $a\text{ || }b$(If sum of interior angles is $180\degree$, then the lines are parallel)