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Program to calculate area and perimeter of equilateral triangle
  • Last Updated : 18 Oct, 2019

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.

    Area of Equilateral triangle :

  • 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.
    ?>


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

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