# Modify Heron's Formula

```eval_rst
Modify :download:`herons_formula.py <examples/herons_formula.py>` to include a check to ensure the lengths of sides ``a``, ``b``, and ``c`` are valid lengths for a triangle. Raise the appropriate error if they are not.
```

1. Obviously, triangles cannot have negative side-lengths or side-lengths of `0`.
2. Not so obvious, certain length combinations are not possible triangles. For example having side lengths of `100`, `1`, and `1` wouldn't create a triangle.


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©2021 Daniel Gallo

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