73 + j42 means it has an active resistance plus reactance. But this "active" resistance is not a DC resistance, right? We can't just measure 73 ohm with a multimeter since the circuit is open. What closes it then? Let's say the reactive part is zero. How do we measure 73 ohm? By measuring current and voltage? But what causes resistance and what kind of resistance is that since it is only measurable as a ratio of AC current to AC voltage but cannot be measured as a DC resistance?