Answer: Transitive property of Equality.
Therefore if ∠XYZ≅∠PDQ and ∠PDQ≅∠ABC then by transitive property of equality we have ∠XYZ≅∠ABC.
The law of transitivity tells that if a equals to b and b equals to c then a equals to c.
For example If Jane has same height of Susan and Susan has same height of Tina then Jane has same height of Tina.