如图,在三角形abc中,m是bc的中点,an平分角bac,bn⊥an,若ab=28,ac=38,求m

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延长bn,交ac于点d.
在△adn和△abn中,∠dan = ∠ban ,an是公共边,∠and = 90°= ∠anb ,
所以,△adn ≌ △abn ,可得：ad = ab ,nd = nb .
mn是△bcd的中位线,可得：mn = (1/2)cd = (1/2)(ac-ad) = (1/2)(ac-ab) = 5 .
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供参考答案1:
5