The dependent current source shown in Figure

In the network of Figure, the maximum power is delivered to R_L if its value is

In figure, the switch was closed for a long time before opening at t = 0. the voltage V_x at t = 0⁺ is

If the 3-phase balanced source in Fig. delivers 1500 W at a leading power factor of 0.844, then the value of Z_L (in ohm) is approximately