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Step 1:

Millmans theorem:

Millmans theorem is applicable to a circuit which may contain only voltage sources in parallel or a mixture of voltage and current sources connected in parallel.

This theorem is nothing but a combination of Thevenins Theorem and Nortons Theorem.

Millman states that the voltage at the ends of the circuit is given by

Where is the resistance at the voltage sources.

And is the resistance on the branch with no source or generators.

For our circuit,

voltage at the end of the nodes A and B is

.

Find the Thevinins equivalent resistance of the circuit.  

1.Open the load resistor. 

2.Open Current Sources and Short Voltage Sources.  

3.Calculate the Open Circuit Resistance. This is the Thevenin Resistance (R_TH). 

Redraw the circuit :

Step 2: 

Observe the circuit:

.

can be written in polar form as .  

can be written in polar form as .

Three impedances are in parallel.

. 

Step 3: 

Observe the circuit:

can be written in polar form as .

.

.

can be written in polar form as .

Substitute corresponding values in the .

can be written in polar form as .