Question 2.Q.21: The impedance of each branch of a delta-connected circuit is......

When three equal impedances are in delta, equivalent star impedance of each branch will be 1/3 times the delta impedance.

Given that,\bar{Z}_{\text{delta }}=\sqrt{3} \bar{Z}

\therefore \overline{ Z }_{\text {star }}=\frac{1}{3} \times \overline{ Z }_{\text {delta }}=\frac{1}{3} \times \sqrt{3} \overline{ Z }=\frac{\overline{ Z }}{\sqrt{3}}