This is a calculator which assumes you are able to short out and measure each resistor of this triangular resistor setup.
This is a black-box with 3 terminals exposed
Follow the bouncing ball...
- Short out R1 (wire across a,b) to give you R2 in parallel with R3. See?
- Measure resistance with probes at a,c. This is Rac
- Short out R2 (wire across b,c).
- Measure resistance with probes at a,b. This is Rab
- Short out R3 (wire across a,c).
- Measure resistance with probes at b,c. This is Rbc