C#: Check whether a triangle is Equilateral, Isosceles or Scalene

Last update on August 20 2025 12:38:20 (UTC/GMT +8 hours)

Write a C# Sharp program to check whether a triangle is Equilateral, Isosceles or Scalene.

C# Sharp: Check whether a triangle is Equilateral, Isosceles or Scalene.

Sample Solution:-

C# Sharp Code:

using System;  // Importing the System namespace

public class Exercise14  // Declaration of the Exercise14 class
{  
    public static void Main()  // Entry point of the program
    {  
        int sidea, sideb, sidec;  // Declaration of variables to store triangle sides
        Console.Write("\n\n");  // Printing new lines
        Console.Write("Check whether a triangle is Equilateral, Isosceles or Scalene:\n");  // Displaying the purpose of the program
        Console.Write("----------------------------------------------------------------");  // Displaying a separator
        Console.Write("\n\n");

        // Prompting user to input the three sides of a triangle
        Console.Write("Input side 1 of triangle: ");
        sidea = Convert.ToInt32(Console.ReadLine());

        Console.Write("Input side 2 of triangle: ");
        sideb = Convert.ToInt32(Console.ReadLine());

        Console.Write("Input side 3 of triangle: ");
        sidec = Convert.ToInt32(Console.ReadLine());

        // Checking conditions to determine the type of triangle based on side lengths
        if (sidea == sideb && sideb == sidec) 
        {  
            Console.Write("This is an equilateral triangle.\n");  // Printing a message for an equilateral triangle
        }  
        else if (sidea == sideb || sidea == sidec || sideb == sidec) 
        {  
            Console.Write("This is an isosceles triangle.\n");  // Printing a message for an isosceles triangle
        }  
        else 
        {  
            Console.Write("This is a scalene triangle.\n");  // Printing a message for a scalene triangle
        }  
    } 
}

Sample Output:

Check whether a triangle is Equilateral, Isosceles or Scalene:                                                
----------------------------------------------------------------                                                                                                    
Input side 1 of triangle: 40                                                                                  
Input side 2 of triangle: 20                                                                                  
Input side 3 of triangle: 20                                                                                  
This is an isosceles triangle.

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