设AE=x,CD=h.1/2(5x-(5-x)*h)=3,5x-5h+xh=6,x=(6+5h)/(5+h)
又△ABE相似于△CDE,则x/(5-x)=5/h,xh=25-5x,x=25/(5+h)
则6+5h=25,h=19/5
所以,CD=19/5
设AE=x,CD=h.1/2(5x-(5-x)*h)=3,5x-5h+xh=6,x=(6+5h)/(5+h)
又△ABE相似于△CDE,则x/(5-x)=5/h,xh=25-5x,x=25/(5+h)
则6+5h=25,h=19/5
所以,CD=19/5