如图,点M分线段AB为5:7,点N分线段AB为5:11,且MN=10,求AB的场
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![如图,点M分线段AB为5:7,点N分线段AB为5:11,且MN=10,求AB的场](/uploads/image/f/3607371-27-1.jpg?t=%E5%A6%82%E5%9B%BE%2C%E7%82%B9M%E5%88%86%E7%BA%BF%E6%AE%B5AB%E4%B8%BA5%3A7%2C%E7%82%B9N%E5%88%86%E7%BA%BF%E6%AE%B5AB%E4%B8%BA5%3A11%2C%E4%B8%94MN%3D10%2C%E6%B1%82AB%E7%9A%84%E5%9C%BA)
设AB=X则AC=2X/3AD=X/4所以CD=AC-AD=5X/12=10X=24cm
MA=5/12ABNA=5/16ABMN=MA-NA=5/48AB=10所以AB=96
你做得对,不用我再写一遍了
AC=AB/2AD=3/5*ABCD=AD-AC=AB*3/5-AB/2=AB(6/10-5/10)=AB*1/10AB=CD*10=70cm再问:很好,没有更好的就选你了再答:谢谢,得到你的肯定
AC:CB=5:3AD:DB=3:5AC=5/8*ABDB=5/8*ABAC+DB=5/8*AB+5/8*ABAB+CD=5/4*ABCD=1/4*ABAB=4*CD=4*10=40(CM)
由题意可知:AC=(5/8)AB,AD=(3/8)ABCD=AC-AD=(1/4)ABAB=4CD=40cm
因为cd=ac-ad=5/12ab-5/16ab=5/48ab所以ab=48/5cd=48/5*10=96cm
10/(11/(11+5)-7/(5+7))=9610/(7/(5+7)-5/(5+11))
∵C点分线段AB为3比5D分线段AB为3比7∴AC:BC=3:5AD:BD=3:7又∵AB=40∴AC=15BD=40*7/10=28∴DC=BD+AC-AB=15+28-40=3
设AB的长为xcm,根据题意得:512x-516x=2,解得x=19.2.∴AB的长为19.2cm.
CD=AC-AD=1/3AB-1/4AB=1/12AB=2AB=24再问:用方程怎么算啊再答:设AB长度为a则AC=1/3a,AD=1/4aCD=1/3a-1/4a=21/12a=2a=24一样的,学
AM=5/(5+7)*AB=5AB/12AN=5/(5+11)*AB=5AB/16MN=AM-AN=5AB/12-5AB/16=(5*4AB-5*3AB)/48=5AB/48=10AB/48=2AB=
∵AC;BC=5:7∴AC=AB×5/(5+7)=5/12AB∵AD:BD=5:11∴AD=AB×5/(5+11)=5/16AB∴CD=AC-AD=5/12AB-5/16AB=5/48AB∵CD=15
/>∵AC:BC=5:7∴AC=5/(5+7)×AB=5/12AB∵AD:BD=5:11∴AD=5/(5+11)×AB=5/16AB∴CD=AC-AD=5/12AB-5/16AB=(20-15)/48
点C分线段AB5:7∴AC=5/12AB点D分线段AB为5:11∴AD=5/16AB∵CD=AC-AD=5㎝∴5/12AB-5/16AB=5㎝AB=48㎝
AC=5/12ABAD=5/16ABCD=AC-AD =(5/12-5/16)AB =5/48AB =5则,5/48
A——D—C——B∵AC:BC=5:7∴AC=5/(5+7)×AB=5/12AB∵AD:BD=5:11∴AD=5/(5+11)×AB=5/16AB∴CD=AC-AD=5/12AB-5/16AB=(20
P在AB之间﹙包括与A,B重合﹚时,MN显然是5现在看P在A的左边,设PA=2a,即PM=MA=a,PN=PA+AN=2a+AN=NB=﹙10+2a﹚/2=5+a∴AN=5-a,MN=MA+AN=a+