How do you find Rt (total resistance) in a series-parallel circuit?

Hehehe.  You have to understand what they really are.
It's done in 2 steps:

1.) Find 2 resistors that are obviously connected in series (or parallel) and replace them by a single equivalent resistance.  Redraw the circuit replacing them with this single resistance.

2.) Repeat step 1 until there is only one resistor remaining.  It is Rt

Doug

measure them with a meter, if necessary desolder one end to confirm, don't forget in ac circuits capacators have resistance at different frequencies.

Any resistor that is hooked to another on one side only is in series.  You treat it as a series "branch".  Just keep combining series components until you can't anymore.  Each time you change something draw an equivalent circuit.  Then you start combining parallel branches.

To find total resistance in a series-parallel circuit using circuit analysis is done by first labeling the resistors, finding the ohms's value, and finally identifying each resistors relation with its neighboring components. Total resistance in series is found by using this equation: Rs= R1 + R2 + ...Rn. Total resistance in parallel can be found using this equation: Rp= (R1 x R2)/(R1 + R2)

Without purely measuring with an Ohm meter (which ideally will not give you the theoretical or calculated resistance due to temperature and nonideal laboratory conditions) one must slowly deduct a smaller circuit composed of the equivalent resistance. Find the resistors that are in parallel together and redraw the circuit with those resistors as a single equivalent resistor and do the same with those in series. You can either do this until you have one resistor which is the total resistance of all the equivalent resistances or (how I do it so I dont have to redraw multiple circuits) find which resistors I can translate into equivalent resistances so that all the new equivalent resistors are either all parallel or all in series. Then I find their equivalent resistance (which I know is the same as finding 1 but your teacher will follow it without having to deduce to 1 resistor).