C++ Exercises: Calculate area of an equilateral triangle

Last update on August 11 2025 12:58:13 (UTC/GMT +8 hours)

Equilateral Triangle Area

Write a C++ program to calculate the area of an equilateral triangle.

Visual Presentation:

C++ Exercises: Calculate area of an equilateral triangle

Sample Solution:

C++ Code :

#include<iostream> // Including input-output stream header file
using namespace std; // Using the standard namespace
#include<math.h> // Including the math library header file for mathematical operations

int main() { // Start of the main function

    float s1; // Declaring a variable to store the side length of the equilateral triangle
    float area; // Declaring a variable to store the area of the equilateral triangle

    cout << "\n\n Calculate the area of the Equilateral Triangle :\n"; // Displaying the purpose of the program
    cout << " ----------------------------------------------------\n"; 

    cout << " Input the value of the side of the equilateral triangle: "; // Prompting the user to input the side length
    cin >> s1; // Taking input of the side length from the user

    area = sqrt(3) / 4 * (s1 * s1); // Calculating the area of the equilateral triangle using the formula
    cout << " The area of the equilateral triangle is: " << area << endl; // Displaying the calculated area

    cout << endl; // Displaying an empty line for better readability
    return 0; // Returning 0 to indicate successful program execution
}

Sample Output:

Calculate the area of the Equilateral Triangle :                      
 ----------------------------------------------------                  
 Input the value of the side of the equilateral triangle: 5            
 The area of equilateral triangle is: 10.8253

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program that calculates the area of an equilateral triangle using both the standard formula and Heron’s formula for verification.
Write a C++ program to compute the area of an equilateral triangle, then scale the triangle by a factor and recalculate the area.
Write a C++ program that takes the side of an equilateral triangle as input and outputs the area rounded to four decimal places using fixed-point notation.
Write a C++ program to calculate the area of an equilateral triangle and compare it with the area of a triangle of the same perimeter.

Go to:

PREV : Third Angle of Triangle.
NEXT : Simple Interest Calculation.

C++ Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.