Solve for Req with T to Delta Transform

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The discussion revolves around finding the equivalent resistance (Req) in a circuit using both direct calculations and a T to Delta transformation. The initial calculation yielded a correct Req of 32.5 ohms without redrawing the circuit. However, when attempting to apply the T to Delta transformation, the participant encountered discrepancies in their calculations, particularly overlooking the 25-ohm resistor. The confusion stems from misapplying the transformation rules and not accounting for all resistors in the circuit, leading to incorrect results. Properly accounting for all components is crucial for accurate transformations and calculations.
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Homework Statement


Find Req in the given circuit
upload_2016-9-26_13-10-23.png


Homework Equations


Series: req = r1+r2...
parallel: 1/req = 1/r1 + 1/r2 ...

The Attempt at a Solution


Without redrawing the circuit I do:
12||60 = 10
10+20 = 30
30 || 30 = 15
15+10 = 25
25||25 = 12.5
12.5+15+5 = 32.5 = Req
This is the correct answer.

upload_2016-9-26_13-10-3.png

However if I redrew the T to a delta I no longer can get the right answer.
108 || 0 = 0
(36 || 30) || (180 || 10) = 6
6||25...
and so on

Where am I going wrong in my logic? Am I not allowed to do this sort of transformation on this problem?
 

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zr95 said:
(36 || 30) || (180 || 10) = 6

Why is the 180 in parallel with the 10?
 
I completely looked over the 25 ohm resistor when I did that. Thanks.
 

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