Question

如图,△ABC∽△A'B'C',相似比为k,点D,D'分别在BC和B'C'上,且BD:CD=B'D':C'D'=1:2,

Answer 1

评价手册第81页第2题

答：AD/A'D'=K

证明：

∵BD/CD=B'D'/C'D'

∴BD/BC=B'D'/B'C'

∴BD/B'D'=BC/B'C'

∵△ABC∽△A'B'C'

∴∠B=∠B'

AB/A'B'=BC/B'C'=K

所以BD/B'D'=AB/A'B'=K

∴△ABD∽△A'B'D'

∴AD/A'D'=AB/A'B'=K

证完