Calculate output impedance of emitter follower
Those formulas with Zin and Zout are valid only for weak AC voltages which ride on the DC bias voltage. You can calculate with them only how much weak AC signals get amplified or attenuated and how strong AC currents they cause as summed to idle state DC current.

ADD: There's comments which state that the formulas are inaccurate. That's true, the formulas  assume transistor works for signal AC component like an ideal by current controlled current source.

The idle state DC current and voltage (=Operating point, bias point) must be calculated with DC model where BE junction is considered to be a diode which has few hundred millivolts voltage drop, for simplicity that voltage drop is often assumed to be 600...700mV although it's actually determined in a complex way by the nonlinear diode law.