三角形ABC中,AB=AC,BD为中线,求证3AB=2BDhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.htmlhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html#IMG=eae670df330b15
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![三角形ABC中,AB=AC,BD为中线,求证3AB=2BDhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.htmlhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html#IMG=eae670df330b15](/uploads/image/z/12681613-37-3.jpg?t=%E4%B8%89%E8%A7%92%E5%BD%A2ABC%E4%B8%AD%2CAB%3DAC%2CBD%E4%B8%BA%E4%B8%AD%E7%BA%BF%2C%E6%B1%82%E8%AF%813AB%3D2BDhttp%3A%2F%2Fhi.baidu.com%2Fxujinyi%25C4%25A7%25BB%25C3%25CA%25C0%25BD%25E7%2Falbum%2Fitem%2F8800bc583a880bdd9c8204b0.htmlhttp%3A%2F%2Fhi.baidu.com%2Fxujinyi%25C4%25A7%25BB%25C3%25CA%25C0%25BD%25E7%2Falbum%2Fitem%2F8800bc583a880bdd9c8204b0.html%23IMG%3Deae670df330b15)
三角形ABC中,AB=AC,BD为中线,求证3AB=2BDhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.htmlhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html#IMG=eae670df330b15
三角形ABC中,AB=AC,BD为中线,求证3AB=2BD
http://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html
http://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html#IMG=eae670df330b15164854036b
三角形ABC中,AB=AC,BD为中线,求证3AB=2BDhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.htmlhttp://hi.baidu.com/xujinyi%C4%A7%BB%C3%CA%C0%BD%E7/album/item/8800bc583a880bdd9c8204b0.html#IMG=eae670df330b15
求证的应该是3AB>2BD吧,这题错了啊!
应该是:
不成立
证明:
AB+AD>BD
2AB+2AD>2BD
又2AD=AC=AB
∴2AB+AB>2BD
∴3AB>2BD
不成立,可以以等边三角形为例,设AB=1,BD=(根号3)/2
3AB不等于2BD