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∵∠BAC+∠B+∠C=180°,∴∠B+∠C=180°-78°=102°,∵∠2=∠B+∠1,而∠1=∠B,∠C=∠2,∴∠C=2∠1,∴∠1+2∠1=102°,∴∠1=34°,∴∠DAC=∠BAC-∠1=78°-34°=44°.
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