In order for three line segments to form a triangle with non-zero area, they must satisfy the "triangle inequality." There are several ways to express this, but perhaps the simplest is ...
a + b > c
where a, b, and c are the lengths of sides in order from shortest to longest.
Here, that means the requirement for a triangle is ...
4 + 4 > 7 . . . . true, so a triangle can be formed
The triangle inequality is satisfied by these segment lengths.
