设大正方形边长是a,小正方形边长是b(a>0,b>0,a>b)
阴影部分面积=a²+b²-△AFG-△DEF-△ABD
=a²+b²-1/2a(a-b)-1/2b²-1/2a(a+b)
=a²+b²-1/2a²+1/2ab-1/2b²-1/2a²-1/2ab
=1/2b²
得证
设大正方形边长是a,小正方形边长是b(a>0,b>0,a>b)
阴影部分面积=a²+b²-△AFG-△DEF-△ABD
=a²+b²-1/2a(a-b)-1/2b²-1/2a(a+b)
=a²+b²-1/2a²+1/2ab-1/2b²-1/2a²-1/2ab
=1/2b²
得证