How do I find the resistance between three terminals?
The first helpful step is to re-draw the schematic:







simulate this circuit &ndash; Schematic created using CircuitLab

Here I've ignored all other terminals because they don't matter. Once you can prove to yourself that the two circuits are equivalent, then prove to yourself that R6 has no effect and can be dropped. Re-drawing the circuit again,







simulate this circuit

The answer should become obvious now.