So far, we designed nine classes and identified the necessary fields for each of them. Now, it is time to add the necessary pieces of code that work with the previously defined fields to perform all the necessary tasks, that is, to calculate perimeters and areas. We have to make sure that each class has the necessary encapsulated functions that process the property values specified in the objects to perform all the tasks.

Let's forget a bit about similarities between the different classes. We will work with them individually as if we didn't have the necessary knowledge of geometric formulas. We will start with the Circle class. We need pieces of code that allow each instance of this class to use the value of the radius property to calculate the area and perimeter.