Triangle Fundimentals

Question

Given a triangle ABC, D is a point on AB, AC=7, AD=6, and BC=18.

The length of  could be __________ . (There are multiple answers)

Answer 1

The length of AB: 11 < AB < 25

AB = AD + DB

11 < AD + DB < 25

11 < 6 + DB < 25

5 < DB < 19