Plss help me:( An impedance coil has a resistance of 20 ohms and an inductive reactance of 40 ohms . For what value of series resistance will the overall power factor?

Analyze the factors that influence the choice between the following pairs of processes to make the products indicated: i) sand casting versus die casting of an electric-motor housing ii) thread rolling versus machining of a bolt for high-strength application. (co3/c5)