Question

Find R between A and B of the circuit​

Answer 1

the easiest way to solve it, is by using folding symmetry

just fold the common part and double the resistance

(as shown in the attachment)

If u look at the circuit clearly a wheatstone bridge is formed

hence the middle 2 r Resistor can be neglected

Step 1

2r and 2 r are in series

Rs =4 r

Step 2

2r and 2 r are in series

Rs =4 r

Step 3

4r and 4r are in parallel

Rp=4r/2 =2 r

Rp=2 r