In this tutorial, we will be learning about the usage of Pi in Python. Pi is an essential mathematical constant, usually used in calculations related to circles and trigonometry. Pi is approximately equal to 3.14159265359.

So, understanding how to use and implement Pi in Python is beneficial for various mathematical and scientific computations. We will cover the use of the **Python math library** and **numpy** to work with Pi and explore some applications related to circle calculations.

### Step 1: Importing the math library

To use the constant Pi in Python, we need to import the **math** library. This library provides access to mathematical functions and constants. To import the math library, you can use the following code:

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import math |

After importing the library, you can use the constant Pi with the help of the **math** module.

### Step 2: Accessing the Pi constant

To access the value of Pi, use the following code:

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pi_value = math.pi print(pi_value) |

This code will output the value of Pi as given below:

3.141592653589793

You can also directly print the value of Pi by using **math.pi** as shown below:

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print(math.pi) |

Although the Pi value we have been using is an approximation, it is precise enough for most purposes and calculations.

### Step 3: Calculating Circumference, Area, and Volume

Now let’s use Pi to calculate the **circumference** and **area** of a circle and the **volume** of a sphere. The formulae for these calculations are as follows:

- Circumference of a circle: 2 * Pi * radius
- Area of a circle: Pi * (radius ** 2)
- Volume of a sphere: (4/3) * Pi * (radius ** 3)

Let’s write a Python code to perform these calculations:

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# Define the radius radius = 3 # Calculate the circumference circumference = 2 * math.pi * radius # Calculate the area area = math.pi * (radius ** 2) # Calculate the volume volume = (4/3) * math.pi * (radius ** 3) # Print the results print("Circumference:", circumference) print("Area:", area) print("Volume:", volume) |

The output of this code will be:

Circumference: 18.84955592153876 Area: 28.274333882308138 Volume: 113.09733552923254

### Step 4: Using NumPy for Pi

Aside from the math library, you can also use the **numpy** library to work with Pi. Numpy is a powerful library for numerical operations and provides the constant Pi as well. First, let’s install numpy using the following command:

pip install numpy

Now, we can import the numpy library in our Python code and access the value of Pi:

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import numpy as np pi_value = np.pi print(pi_value) |

This code will output the same value of Pi as before:

3.141592653589793

Remember that you may use either the **math** library or **numpy** for Pi, depending on your preference and the specific requirements of your project.

## Full code:

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import math import numpy as np # Define the radius radius = 3 # Calculate the circumference circumference = 2 * math.pi * radius # Calculate the area area = np.pi * (radius ** 2) # Calculate the volume of a sphere volume = (4/3) * np.pi * (radius ** 3) # Print the results print("Circumference:", circumference) print("Area:", area) print("Volume:", volume) |

## Conclusion

In this tutorial, we learned how to use the constant Pi in Python using the **math** and **numpy** libraries. We also demonstrated its practical application by calculating the circumference, area, and volume related to circles and spheres. Understanding the usage of Pi in Python is essential for any mathematical and scientific computation involving circles and trigonometric functions.