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如图示,设BD=x,DO=y,由MN\于AC有EG/EN=EO/ED,即EG/(EG+GN)=(x-y)/y.(其中ED=BD=x),由EG/(EG+GN)=(x-y)/y得EG/NG=(x-y)/y.
设MN长为a,AC长为b,则a/b=x/(x+y),得a=bx/(x+y)①
由三角形MBN与梯形AMNC面积相等,有面积公式有ax/2=(a+b)y/2②
将①式代入②式得xx-2xy-yy=0,即(x-y)(x-y)-2yy=0,
即(x-y)(x-y)=2yy,开根号得x-y=√2y,即(x-y)/y=√2
由AE\NC有AE/NC=EG/GN=√2
1年前
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