Abc is a triangle in which angle b= 2 angle c. d is a point on bc such that ad bisects angle bac and ab=cd. prove that angle bac=72°

So Triangle ABC and ADC are similar (two sides and one angle is equal)so angle CAD = angle ACB =cso angle BAC=2cand in triangle ABCangle BAC + angle ABC + angle ACB = 2c+2c+c = 5c = 180c=180/5 = 36angle BAC =2c=2*36 =72