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Circuit after Δ Y transformation of top bridge .. can now use parallel/serial combinations rather than source injection to find Thevenin's resistanceThe bridge circuit example was solved with source injection, but could have been solved with a Y Δ transformation.
Example23g.png
The 5,2 and 3 ohm resistors form a Δ that could be transformed into a Y.

The equations are:


Now Thevenin's resistance can be solved by parallel and serial combinations:

Which is the same value found through source injection.