A thermodynamic system undergoes cyclic process ABCDA as shown in fig. The work done by the system in the cycle is: 

zero

Work done by the system in the cycle = Area under P – V curve & V – axis

For clockwise work done is positive ; For anticlockwise work done is negative

W_ADEA = \(\frac{1}{2} (2P_o - P_o) (2V_o - V_o)\)

W_EBCE = - \(\frac{1}{2} (3P_o - 2P_o) (2V_o - V_o)\)

W_EBCE - W_ADEA = 0