How vth and rth are calculated?

Vth (thevenin equivalent voltage) is calculated by determining the open-circuit voltage at the terminals of the circuit, which means measuring the voltage when no load is connected. Rth (thevenin equivalent resistance) is found by turning off all independent sources (replacing voltage sources with short circuits and current sources with open circuits) and calculating the equivalent resistance seen from the terminals. These two parameters are essential for simplifying complex circuits into a simple voltage source and resistance for easier analysis.