Use the link below for more help/practice.
https://www.khanacademy.org/math/geometry/basic-geometry/triangle_inequality_theorem/v/triangle-inqequality-theorem
http://www.brightstorm.com/math/geometry/triangles/triangle-side-inequalities/
https://www.youtube.com/watch?v=7PfLSEpPQns
Homework: Complete WS 4.7 A & B.