The resistances of the various arms of a bridge are given in Figure A. The supply alternating output power and current are 10W and 10sinθ A respectively. Determine the current’s range value (in terms of ammeters) of I1, under the condition where, the direction of the resultant power for that particular resistance must be according to the first quadrant of the polar phase. While in proposing the solution, you can always assume and modify the existing circuit, but those should be clearly stated and explained!

I'm already try it and become confused with this question since I did'nt know how to find the input voltage for this question...correct me if I'm wrong..

 

Your diagram is a DC supply not AC, you cant find any voltages as you dont know what the supply is?