# Triangle Inequality Theorem

Any side of a triangle must be **shorter** than the other two sides added together.

Why? Well imagine one side is **not** shorter:

- If a side is
**longer**than the other two sides there is a gap: - If a side is
**equal**to the other two sides it is not a triangle (just a straight line back and forth).

Try moving the points below:

images/triangle.js?mode=inequal

When the three sides are **a**, **b** and **c**, we can write:

- a < b + c
- b < a + c
- c < a + b

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