△DAC:
∠ACD =180°-∠DAC-∠D =180°-42°-69° =69°
∠ACD=∠D => △DAC - равнобедренный, AD=AC
△CAB:
AD=AC=AB => △CAB - равнобедренный, ∠ACB=∠ABC
∠ABC =(180°-∠CAB)/2 =(180°-54°)/2 =63°
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△DAC:
∠ACD =180°-∠DAC-∠D =180°-42°-69° =69°
∠ACD=∠D => △DAC - равнобедренный, AD=AC
△CAB:
AD=AC=AB => △CAB - равнобедренный, ∠ACB=∠ABC
∠ABC =(180°-∠CAB)/2 =(180°-54°)/2 =63°