# OO Triangle lab

## Triangle

### Objectives

1. Define a custom error and use it.

### Instructions

* Write a `Triangle` class that accepts three arguments on initialization. Each argument is a length of one of the three sides of the triangle.
* Give your Triangles an instance method, `kind` that returns, as a symbol, its type. The valid types are:

1. `:equilateral`
2. `:isosceles`
3. `:scalene`

* The `kind` method should raise a custom error, `TriangleError` if the triangle is invalid. Check out the hint below to understand what makes a triangle invalid. Write a custom error class, `TriangleError` and inherit it from `StandardError`. This custom error class should be defined in the same file as the `Triangle` class, inside the `Triangle` class definition. Like this:

```
# lib/triangle.rb

class Triangle
  # triangle code

  class TriangleError < StandardError
    # triangle error code
  end
end
```

### Hint

The sum of the lengths of any two sides of a triangle always exceeds the length of the third side. This is a principle known as the *triangle inequality*.

Further, each side must be larger than 0.

### Resources

* [Exception Handling](http://www.skorks.com/2009/09/ruby-exceptions-and-exception-handling/)
* [Basic Mathematics](http://www.basic-mathematics.com/) - [Types of Triangles](http://www.basic-mathematics.com/types-of-triangles.html)

View [Triangle](https://github.com/learn-co-curriculum/triangle-classification) on Learn.co and start learning to code for free.