As shown in Fig. , delta DAC has been reduced to its equivalent star.
RD = (2 x 1)/(2 + 1 + 1) = 0.5Ω, RA = 1/4 = 0.25Ω, RC = 2/4 = 0.5Ω
Hence, the original network of Fig. is reduced to the one shown in Fig.. As seen, there are two parallel paths between points N and B, one of resistance 1.25 Ω and the other of resistance 1.5 Ω. Their combined resistance is
= (1.25 x 1.5)/(1.25 + 1.5) = 15/22Ω
Total resistance of the network between points D and B is
= 0.5 + 15/22 = 13/11Ω
