Question

find the equivalent resistance across the two ends A and B of the following

Answer 1

All the three resistances are in parallel, we get
1/Rab=1/R1+1/R2+1/R3=> 1/Rab=R1R2+R2R3+R3R1/R1R2R3 => Rab=R1R2R3/R1R2+R2R3+R3R1 .