Two Stage Amplifier -- Find the Input Resistance

[IronaSona]

Homework Statement

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Relevant Equations

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Am trying to find Effects of Feedback - Input resistance of this circuit.
Is this the formula that in need to use to find the input resistance of this circuit ?

 

[berkeman]

Where do you see feedback in this amp? And R1 and R2 are in parallel with the input impedance of Q1...