Program to calculate area and perimeter of equilateral triangle

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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

C++

// 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

// 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. 

Python

# 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#

// 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 
// 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. 
?> 

Javascript

<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>

Output

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

Time Complexity: O(1)

Auxiliary Space: O(1)

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