已知四边形ABCD,∠B=∠ACD,AB=6,BC=4,AC=5,CD=7.5,求AD的长.

问题描述:

已知四边形ABCD,∠B=∠ACD,AB=6,BC=4,AC=5,CD=7.5,求AD的长.


∵AB=6,BC=4,AC=5,CD=7.5,

AB
CD
BC
AC
4
5

且∠B=∠ACD,
∴△ABC∽△DCA,
AC
AD
BC
AC
=
4
5

5
AD
4
5

∴AD=
25
4