We develop some exercises in Python in order to consolidate what we have studied so far.

## First exercise in Python

Calculate the area of a circle by taking the radius as input.

So here is the solution to the simple problem in Python:

>>> radius = **float**(input())

5.5

>>> PiGreco = 3.14

>>> area = PiGreco*radius *radius

>>> print(‘the area of the circle of radius’, radius, ‘ is:’, area)

the area of the circle of radius 5.5 is 94,985.

The data to be taken as input is therefore only the radius. PiGreco is a constant value to which I assign the approximate value 3.14.

In Python there is no significant difference between declaring a constant or a variable.

Recall that the constant represents data that does not change during the execution of the program, unlike the variable.

Later we will use the **math library** and therefore the constant **math.pi**.

## Second exercise in Python

Among the Python exercises that we will deal with today, there is also this very simple one:

Take the price of a product as input and discount it by 30%.

>>> price = **float**(input())

34.6

>>> price -= price *30/100

>>> price

24.22

The expression price -= price * 30/100 is nothing more than the abbreviated form of price = price – price * 30/100, as we explained in the lesson on assignment operators.

You could also write price * = 70/100 or price * = 0.7.

I did everything using a single variable because the price variable is no longer used within the program. If, on the other hand, it is necessary, it would be advisable to create another variable.

## Third exercise in Python

We continue with other exercises in Python and therefore I propose the following:

Calculate the area of a trapezoid by taking as input the major base, the minor base and the height.

The resolution of this algorithm is therefore very simple:

>>> B = int(input()) #I take the major base as input.

58

>>> b = int(input()) #I take the minor base as input.

30

>>> h = int(input()) #I take the height as input.

16

>>> area=(B+b)*h/2 #calculating the area of the trapezium

>>> print(‘the trapezius area is: ‘, area) #I view the area

the trapezius area is 704.0.

## Conclusion

In this tutorial I have explained some very simple exercises in Python, in the next lessons we will practice again.