THANKSTHANKS
THANKS∵∠ABC=∠C=2∠A,∠A+∠ABC+∠C=180∴∠A+2∠A+2∠A=180∴∠A=36∴∠C=2∠A=72∵BD⊥AC∴∠DBC+∠C=90∴∠DBC=90-∠C=18°