Where does Zi = hie+1(1+hfe)RE come from in a BJT from Hybrid Model?
To determine the input resistance of a simple common-collector configuration you have to replace the transistor symbol by its equivalent hybrid-\$\pi\$ model. The common-collector configuration is shown below and the transistor simplified linear model is in the right-side of the picture:



Then, to determine an input impedance or resistance, you install a current source \$I_T\$ (the stimulus) biasing the terminals across which you want the resistance and you express the voltage \$V_T\$ (the response) that it generates. Then, you simply write \$R_{in}=\frac{V_T}{I_T}\$. Here we go with the drawing:



This is a small-signal model in which we consider the \$V_{cc}\$ rail perfectly decoupled meaning that any modulation applied to the circuit won't make the voltage of this rail move. In other words, its differentiation with respect to time is 0, hence the replacement of the source by a wire. To determine the voltage \$V_T\$, we stack the voltage across \$r_\pi\$ with that across the emitter resistance \$R_E\$. In this drawing, the base current is actually the injected current \$I_T\$. Therefore, \$V_T=i_br_\pi+(\beta i_b +i_b)R_E=i_b(r_\pi+(\beta+1)R_E)=I_T(r_\pi+(\beta+1)R_E)\$.

Now, divide \$V_T\$ by \$I_T\$ and you have \$R_{in}=r_\pi+(\beta+1)R_E\$.