Question

What is the smallest possible number for the 3rd side

Answer 1

11

Explanation:

In order to create a triangle, the two smallest sides must equal the largest side

Here we have 4 and 15. We could say 4+15=19, making 19 the third side.

But what if we made 15 the longest side

That would force us to make the 3rd side 11 instead because 4+11=15. And 11 is smaller than 19