已知△ABC.(1)如图1,若P点为∠ABC和∠ACB的角平分线的交点,试说明:∠P=90゜+12∠A;(2)如图2,若

2025-05-23 14:22:18
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回答1:

解答:证明:(1)∠P=180゜-

1
2
∠ABC-
1
2
∠ACB=180゜-
1
2
(180゜-∠A)=90+
1
2
∠A
(2)∠P=∠PCD-∠PBD=
1
2
∠ACD-
1
2
∠ABC=
1
2
∠A
(3)∠P=180゜-
1
2
∠CBD-
1
2
∠BCE
=180゜-
1
2
(∠CBD+∠BCE)
=180゜-
1
2
(∠A+∠ACB+∠A+∠ABC)
=180゜-
1
2
(180゜+∠A)
=90゜-
1
2
∠A.