Answer:
3 < c < 11
Explanation:
A side of a triangle cannot be greater than the sum of the other two side lengths; otherwise, it would simply be a line.
Similarly, a side of a triangle cannot be less than the difference of the other two side lengths; otherwise it would simply be a line.
7 + 4 = 11, thus c < 11
7 - 4 = 3, thus c > 3
↓
3 < c < 11