The circuit I am interested in is attached. I was just looking for a little input to help me start this problem. As the title states I am just looking to find the -3dB frequency of this circuit.
Write the equation for the output voltage as a function of frequency. Then using that equation, find the frequency that makes the output X times lower than the input where X is given by the equation below.
The circuit begins with a voltage divider that cuts Vsource in half. That's already more than 3dB down (1/√2 ≈ 0.7071). Perhaps you're looking for where it's 3db down compared to a DC input voltage?