解:设AB=9,BC=1,根据勾股定理的AC= 92?12 = 80 =4 5 ,∵S△ABC= 1 2 AC?CB= 1 2 AB?CD,即4 5 ×1=9CD,∴CD= 4 5 9 ,在Rt△ACD中,根据勾股定理得:AD= 80? 80 81 = 80 9 ,BD=9- 80 9 = 1 9 ,则AD:BD=80:1,故答案为:80:1.