How to calculate the area of ​​a circle in Python

The task of calculating the area of ​​a circle in Python involves taking the radius as input, applying the mathematical formula to calculate the area of ​​the circle, and displaying the result.

Formula for calculating the area of ​​a circle:

Diện tích hình tròn = pi * r2

In there:

1. π (pi) is a mathematical constant approximately equal to 3.14159.
2. r is the radius of the circle.

For example, if r = 5 , the area is calculated as: Area of ​​circle = 3.14159 × 5² = 78.53975.

Using math.pi

The math module provides the math.pi constant , which represents the value of π (pi) with high precision. This approach is widely used in mathematical calculations and is considered the standard approach in modern Python programming . It is optimal for general-purpose applications that require precision and speed.

import math r = 5 # radius area = math.pi * (r ** 2) print(area)

Result:

78.53981633974483

Explanation: area is calculated using the formula math.pi * (r ** 2) , where r ** 2 is the square of the radius and math.pi ensures high accuracy for π .

Using math.pow()

The math.pow() function is optimized for power calculations, making it easier to read when dealing with complex exponents. This function is often preferred when working with formulas with many exponents, although it is less common than using ** for simple squares.

import math r = 5 # radius area = math.pi * math.pow(r, 2) print(area)

Result:

78.53981633974483

Explanation: math.pi * math.pow(r, 2) , where math.pow(r, 2) raises the radius to the power of 2, math.pi makes sure to use the exact value of π .

Using numpy.pi

The numpy library is designed for high-performance numerical computations, and numpy.pi provides an accurate value of π. It is particularly efficient when performing large area calculations or working with arrays of radii. This makes it ideal for large-scale calculations.

import numpy as np r = 5 # radius area = np.pi * (r ** 2) print(area)

Result:

78.53981633974483

Explanation: np.pi * (r ** 2) , where np.pi provides a high-precision π value and r ** 2 is the square of the radius.

Using hardcoded pi value

This is a simple, traditional approach, where the value of π is manually set to a constant. It is often used in basic programs or rapid prototyping where accuracy is not a critical factor. While this method is easy to implement, it is less accurate and is generally not recommended for professional or scientific calculations.

PI = 3.142 r = 5 # radius area = PI * (r * r) print(area)

Result:

78.55

Explanation: The area is then calculated using the formula PI * (r * r) , where r * r is the radius squared.