Program to calculate area and perimeter of equilateral triangle

An equilateral triangle is a triangle in which all three sides and angles are equal. All three internal angles of equilateral triangle measures 60 degree.

• If we know the length of each sides of equilateral triangle, then we can use below mentioned formula to calculate area of equilateral triangle.

Area of Equilateral Triangle = (sqrt(3)/4) * a * a    

• If we know the length of altitude of equilateral triangle along with the length of side, then we can use below mentioned formula to calculate it's area.

Area of Equilateral Triangle = (1/2) x Side x Altitude

Perimeter of Equilateral Triangle :

Perimeter of Equilateral Triangle :  3 X a

How does the area formula work?
Let us take a look at below diagram. We know are of a triangle is 1/2 * base * height. The value of h is sqrt(a² – (a/2)²) = sqrt(3) * a / 2. So the area becomes 1/2 * a * (sqrt(3) * a / 2) = (sqrt(3)/4) * a * a

Examples:

Input : side = 4
Output : Area of Equilateral Triangle: 6.9282
        Perimeter of Equilateral Triangle: 12
Input : side = 12
Output : Area of Equilateral Triangle: 62.3538
        Perimeter of Equilateral Triangle: 36

// CPP program to find area
// and perimeter of equilateral triangle
#include <bits/stdc++.h>
using namespace std;

// Function to calculate Area
// of equilateral triangle
float area_equi_triangle(float side)
{
    return sqrt(3) / 4 * side * side;
}

// Function to calculate Perimeter
// of equilateral triangle
float peri_equi_triangle(float side)
{
    return 3 * side;
}

// Driver Code
int main()
{
    float side = 4;
    cout << "Area of Equilateral Triangle: "
        << area_equi_triangle(side) << endl;
    cout << "Perimeter of Equilateral Triangle: "
        << peri_equi_triangle(side);
    return 0;
}

// Java Program to find area and
// perimeter of equilateral triangle
import java.io.*;

class GFG
{
    // Function to calculate
    // Area of equilateral triangle
    static float area_equi_triangle(float side)
    {

        return (float)(((Math.sqrt(3)) / 4) *
                        side * side);
    }

    // Function to calculate
    // Perimeter of equilateral
    // triangle
    static float peri_equi_triangle(float side)
    {
        return 3 * side;
    }
    
    // Driver Code
    public static void main(String arg[])
    {
        float side = 4;
        System.out.print("Area of Equilateral Triangle:");
        System.out.println(area_equi_triangle(side));
        System.out.print("Perimeter of Equilateral Triangle:");
        System.out.println(peri_equi_triangle(side));
    }
}

// This code is contributed
// by Anant Agarwal.

# Python3 program to calculate Area and
# Perimeter of equilateral Triangle

# Importing Math library for sqrt
from math import *

# Function to calculate Area
# of equilateral triangle
def area_equilateral( side ):
    area = (sqrt(3) / 4) * side * side
    print ("Area of Equilateral Triangle: % f"% area)

# Function to calculate Perimeter
# of equilateral triangle
def perimeter( side ):
    perimeter = 3 * side
    print ("Perimeter of Equilateral Triangle: % f"% perimeter)
    
# Driver code
side = 4
area_equilateral( side )
perimeter( side )

// C# Program to find area and
// perimeter of equilateral triangle
using System;

class GFG
{
    // Function to calculate
    // Area of equilateral triangle
    static float area_equi_triangle(float side)
    {

        return (float)(((Math.Sqrt(3)) / 4) *
                        side * side);
    }

    // Function to calculate
    // Perimeter of equilateral
    // triangle
    static float peri_equi_triangle(float side)
    {
        return 3 * side;
    }
    
    // Driver Code
    public static void Main()
    {
        float side = 4;
        Console.Write("Area of Equilateral Triangle:");
        Console.WriteLine(area_equi_triangle(side));
        Console.Write("Perimeter of Equilateral Triangle:");
        Console.WriteLine(peri_equi_triangle(side));
    }
}

// This code is contributed
// by vt_m.

<?php
// PHP program to find area
// and perimeter of equilateral triangle


// Function to calculate Area
// of equilateral triangle
function area_equi_triangle( $side)
{
    return sqrt(3) / 4 * $side * $side;
}

// Function to calculate Perimeter
// of equilateral triangle
function peri_equi_triangle( $side)
{
    return 3 * $side;
}

// Driver Code

$side = 4;
echo("Area of Equilateral Triangle: ");
echo(area_equi_triangle($side));
echo("\n");
echo("Perimeter of Equilateral Triangle: ");
echo( peri_equi_triangle($side));

// This code is contributed
// by vt_m.
?>

<script>
    //Javascript program to find area
    // and perimeter of equilateral triangle
    
    // Function to calculate 
    // Area of equilateral triangle
    function area_equi_triangle(side)
    {
        return (((Math.sqrt(3)) / 4) * side * side).toFixed(4);
    }
    
    // Function to calculate 
    // Perimeter of equilateral
    // triangle
    function peri_equi_triangle(side)
    {
        return 3 * side;
    }
    
    //Driver code
    var side = 4;
    document.write("Area of Equilateral Triangle:");
    document.write(area_equi_triangle(side)+"\n");
    document.write("Perimeter of Equilateral Triangle:");
    document.write(peri_equi_triangle(side)+"\n");
    
    //This code is contributed by shruti456rawal
</script>

Area of Equilateral Triangle: 6.9282
Perimeter of Equilateral Triangle: 12

Time Complexity: O(1)

Auxiliary Space: O(1)