Based on the Triangle Inequality Theorem that states that the sum of any 2 sides of a triangle must be greater than the measure of the third side, we can find what set of lengths cannot form a triangle.
The only set that does not follow the theorem is the set with lengths 7in, 7in, and 15in. It does not follow the theorem because...
7 + 7 < 15 (which should not be true based on the theorem)
