---
id: 5e444147903586ffb414c94f
title: Polygon Area Calculator
challengeType: 10
forumTopicId: 462363
dashedName: polygon-area-calculator
---

# --description--

You will be <a href="https://replit.com/github/freeCodeCamp/boilerplate-polygon-area-calculator" target="_blank" rel="noopener noreferrer nofollow">working on this project with our Replit starter code</a>.

-   Start by importing the project on Replit.
-   Next, you will see a `.replit` window.
-   Select `Use run command` and click the `Done` button.


# --instructions--

In this project you will use object oriented programming to create a Rectangle class and a Square class. The Square class should be a subclass of Rectangle and inherit methods and attributes.

## Rectangle class

When a Rectangle object is created, it should be initialized with `width` and `height` attributes. The class should also contain the following methods:

- `set_width`
- `set_height`
- `get_area`: Returns area (`width * height`)
- `get_perimeter`: Returns perimeter (`2 * width + 2 * height`)
- `get_diagonal`: Returns diagonal (`(width ** 2 + height ** 2) ** .5`)
- `get_picture`: Returns a string that represents the shape using lines of "\*". The number of lines should be equal to the height and the number of "\*" in each line should be equal to the width. There should be a new line (`\n`) at the end of each line. If the width or height is larger than 50, this should return the string: "Too big for picture.".
- `get_amount_inside`: Takes another shape (square or rectangle) as an argument. Returns the number of times the passed in shape could fit inside the shape (with no rotations). For instance, a rectangle with a width of 4 and a height of 8 could fit in two squares with sides of 4.

Additionally, if an instance of a Rectangle is represented as a string, it should look like: `Rectangle(width=5, height=10)`

## Square class

The Square class should be a subclass of Rectangle. When a Square object is created, a single side length is passed in. The `__init__` method should store the side length in both the `width` and `height` attributes from the Rectangle class.

The Square class should be able to access the Rectangle class methods but should also contain a `set_side` method. If an instance of a Square is represented as a string, it should look like: `Square(side=9)`

Additionally, the `set_width` and `set_height` methods on the Square class should set both the width and height.

## Usage example

```py
rect = shape_calculator.Rectangle(10, 5)
print(rect.get_area())
rect.set_height(3)
print(rect.get_perimeter())
print(rect)
print(rect.get_picture())

sq = shape_calculator.Square(9)
print(sq.get_area())
sq.set_side(4)
print(sq.get_diagonal())
print(sq)
print(sq.get_picture())

rect.set_height(8)
rect.set_width(16)
print(rect.get_amount_inside(sq))
```

That code should return:

```bash
50
26
Rectangle(width=10, height=3)
**********
**********
**********

81
5.656854249492381
Square(side=4)
****
****
****
****

8
```

The unit tests for this project are in `test_module.py`.

## Development

Write your code in `shape_calculator.py`. For development, you can use `main.py` to test your `shape_calculator()` function. Click the "run" button and `main.py` will run.

## Testing

We imported the tests from `test_module.py` to `main.py` for your convenience. The tests will run automatically whenever you hit the "run" button.

## Submitting

Copy your project's URL and submit it to freeCodeCamp.

# --hints--

It should create a Rectangle class and Square class and pass all tests.

```js

```

# --solutions--

```js
/**
  Backend challenges don't need solutions,
  because they would need to be tested against a full working project.
  Please check our contributing guidelines to learn more.
*/
```
