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, then the other two sides don't meet:
- 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:
When the three sides are a, b and c, we can write:
- a < b + c
- b < a + c
- c < a + b