I am not very knowledgeable in analyzing biasing circuits but I have understood the following: \$R_1\$ and \$R_2\$ are feedback resistors. This is a voltage amplifier. \$R_L\$ is the load. The output stage of the amplifier is a npn-transistor. the input stage is a differential stage and the peak output voltage is \$v_L = 1.5V\$.
Should I know assume that npn-transistor is a switch and check the two cases? Or how should I proceed. Do I assume anything else about this circuit like that the base currents are 0 and that the base voltages across the differential amplifier stage is zero?