急用!初中数学题,快点,谢谢!
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急用!初中数学题,快点,谢谢!
![急用!初中数学题,快点,谢谢!](/uploads/image/z/17277883-43-3.jpg?t=%E6%80%A5%E7%94%A8%21%E5%88%9D%E4%B8%AD%E6%95%B0%E5%AD%A6%E9%A2%98%2C%E5%BF%AB%E7%82%B9%2C%E8%B0%A2%E8%B0%A2%21)
因为:BC = (1/3)AB = (1/4)CD ,
所以:AB = 3BC ,CD = 4BC ;
因为:E、F分别是AB、CD的中点,
所以:AE = (1/2)AB = (3/2)BC ,DF = (1/2)CD = 2BC ;
因为,AD = AB+CD-BC = 6BC ,
所以,EF = AD-AE-DF = (5/2)BC ;
因为:BC = (2/5)EF = 24 cm ,
所以,AB = 3BC = 72 cm ,CD = 4BC = 96 cm .
所以:AB = 3BC ,CD = 4BC ;
因为:E、F分别是AB、CD的中点,
所以:AE = (1/2)AB = (3/2)BC ,DF = (1/2)CD = 2BC ;
因为,AD = AB+CD-BC = 6BC ,
所以,EF = AD-AE-DF = (5/2)BC ;
因为:BC = (2/5)EF = 24 cm ,
所以,AB = 3BC = 72 cm ,CD = 4BC = 96 cm .