As in right figure，in a quadrilateral ABCD，we have its diagonal AC bisects∠DAB，and AB=21，AD=9，BC=DC=10，then the distance
问题描述：
As in right figure，in a quadrilateral ABCD，we have its diagonal AC bisects∠DAB，and AB=21，AD=9，BC=DC=10，then the distance from point C to line AB is______，and the length of AC is______． （英汉词典：quadrilateral 四边形；bisect 平分）
答
过C作CE⊥AD，CF⊥AB，
∴△CED≌△CFB，
∴DE=FB，
∴9+DE=21-BF，
∴BF=6，
根据勾股定理，可知CF=CE=8，即点C到AB的距离为8．
∴AC=
=
AF2+CF2
=17．
152+82
故答案为：8，17．