求证∠p=90+1/2∠A

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求证∠p=90+1/2∠A
 

∠ABC+∠ACB=180°-∠A
∵BP平分∠ABC CP平分∠ACB
∴∠PBC+∠PCB=1/2(∠ABC+∠ACB)=90°-1/2∠A
故∠P=180°-(∠PBC+∠PCB)=180°-(90°-1/2∠A)=90°+1/2∠A