1. The problem statement, all variables and given/known data demonstrate that the distribution factor is equal to 1 in concentric windings. 2. Relevant equations 3. The attempt at a solution i have tried to solve it doing the equations shown in this page, http://www.electrical4u.com/winding-factor-pitch-factor-distribution-factor/ but i cant reach to the desired conclusion, because the magnitude of the emfs phasors is different when the winding is concentric,also, i am not really sure if i can do the same analogy with the common point O. what am i doing wrong? p.s. Sorry for my bad english.