What does the Triangle Inequality Theorem state?

The Triangle Inequality Theorem states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. This principle is foundational to understanding triangle properties and ensures that the lengths can indeed form a triangle. For example, if one side has a length of 3 and another side has a length of 4, the sum is 7, which is greater than the length of the third side, whether it is 5, 6, or even up to 6.999, thus allowing a triangle to form.

This theorem is essential for validating whether a given set of lengths can create a triangle, helping students and practitioners in geometry understand the relationships between side lengths. It illustrates the relationships and constraints in geometric figures, providing insight into their structure.

Other statements do not align with the Triangle Inequality Theorem: the first statement addresses the sum of angles in a triangle, the second incorrectly references a product rather than a sum, and the last describes an entirely different condition of a triangle, namely, that of an equilateral triangle where all sides are equal.