∵AB=AC
∴∠B=∠C
∵AD=DC
∴∠C=∠4
∴∠3=180°-2∠C
∵AB=BD
∴∠2=∠1=1/2(180°-∠B)=1/2(180°-∠C)
∵∠2+∠3=180°
∴180°-2∠C+1/2(180°-∠C)=180°
∴∠C=36°
∴∠BAC=180°-2∠C
=180°-72°
=108°
∵AB=AC
∴∠B=∠C
∵AD=DC
∴∠C=∠4
∴∠3=180°-2∠C
∵AB=BD
∴∠2=∠1=1/2(180°-∠B)=1/2(180°-∠C)
∵∠2+∠3=180°
∴180°-2∠C+1/2(180°-∠C)=180°
∴∠C=36°
∴∠BAC=180°-2∠C
=180°-72°
=108°