Part of the series

Several example codes

~2 min read • Updated Oct 7, 2025

Program Overview

This Python program reads three side lengths a, b, and c.
It checks whether the triangle is right-angled using the Pythagorean theorem.
If it is, the program calculates and displays:
- Area of the triangle
- Perimeter of the triangle
A helper variable temp is used to store the computed values.


Python Code:


import math

# Read triangle sides
a = float(input("Enter side a: "))
b = float(input("Enter side b: "))
c = float(input("Enter side c: "))

# Sort sides to identify the hypotenuse
sides = sorted([a, b, c])  # sides[0], sides[1], sides[2]

# Check for right triangle using Pythagorean theorem
if math.isclose(sides[0]**2 + sides[1]**2, sides[2]**2, rel_tol=1e-9):
    print("The triangle is right-angled.")

    # Calculate area: base × height ÷ 2
    temp = (sides[0] * sides[1]) / 2
    print(f"Area of the triangle: {temp:.2f}")

    # Calculate perimeter: sum of all sides
    temp = a + b + c
    print(f"Perimeter of the triangle: {temp:.2f}")
else:
    print("The triangle is not right-angled.")

Sample Output:


Enter side a: 3  
Enter side b: 4  
Enter side c: 5  

The triangle is right-angled.  
Area of the triangle: 6.00  
Perimeter of the triangle: 12.00

Step-by-Step Explanation:

- The sides are sorted to identify the largest one as the hypotenuse
- The program checks if a² + b² = c² using math.isclose for precision
- If the triangle is right-angled, it calculates the area and perimeter
- The variable temp is used to store and display each result


Written & researched by Dr. Shahin Siami