# Program to find area of a triangle

Finding area using given sides:

Examples :

Input : a = 5, b = 7, c = 8
Output : Area of a triangle is 17.320508

Input : a = 3, b = 4, c = 5
Output : Area of a triangle is 6.000000


Area of a triangle can simply be evaluated using following formula.

Area = sqrt(s*(s-a)*(s-b)*(s-c))
where a, b and c are lengths of sides of
triangle and s = (a+b+c)/2 ## C++

 // C++ Program to find the area   // of triangle   #include  using namespace std;     float findArea(float a, float b, float c)   {       // Length of sides must be positive       // and sum of any two sides       // must be smaller than third side.       if (a < 0 || b < 0 || c < 0 ||          (a + b <= c) || a + c <= b ||                          b + c <= a)       {           cout << "Not a valid trianglen";           exit(0);       }       float s = (a + b + c) / 2;       return sqrt(s * (s - a) *                       (s - b) * (s - c));   }      // Driver Code  int main()   {       float a = 3.0;       float b = 4.0;       float c = 5.0;          cout << "Area is " << findArea(a, b, c);       return 0;   }      // This code is contributed   // by rathbhupendra

## C

 #include    #include       float findArea(float a, float b, float c)  {      // Length of sides must be positive and sum of any two sides      // must be smaller than third side.      if (a < 0 || b < 0 || c <0 || (a+b <= c) ||          a+c <=b || b+c <=a)      {          printf("Not a valid trianglen");          exit(0);      }      float s = (a+b+c)/2;      return sqrt(s*(s-a)*(s-b)*(s-c));  }     int main()  {      float a = 3.0;      float b = 4.0;      float c = 5.0;         printf("Area is %f", findArea(a, b, c));      return 0;  }

## Java

 // Java program to print  // Floyd's triangle         class Test  {      static float findArea(float a, float b, float c)      {          // Length of sides must be positive and sum of any two sides          // must be smaller than third side.          if (a < 0 || b < 0 || c <0 || (a+b <= c) ||              a+c <=b || b+c <=a)          {              System.out.println("Not a valid triangle");              System.exit(0);          }          float s = (a+b+c)/2;          return (float)Math.sqrt(s*(s-a)*(s-b)*(s-c));      }                 // Driver method      public static void main(String[] args)       {          float a = 3.0f;          float b = 4.0f;          float c = 5.0f;                 System.out.println("Area is " + findArea(a, b, c));      }  }

## Python

 # Python Program to find the area   # of triangle      # Length of sides must be positive   # and sum of any two sides   def findArea(a,b,c):          # must be smaller than third side.       if (a < 0 or b < 0 or c < 0 or (a+b <= c) or (a+c <=b) or (b+c <=a) ):           print('Not a valid trianglen')           return                # calculate the semi-perimeter       s = (a + b + c) / 2            # calculate the area       area = (s * (s - a) * (s - b) * (s - c)) ** 0.5     print('Area of a traingle is %f' %area)         # Initialize first side of traingle   a = 3.0 # Initialize second side of traingle   b = 4.0 # Initialize Third side of traingle   c = 5.0 findArea(a,b,c)      # This code is contributed by Shariq Raza

## C#

 // C# program to print  // Floyd's triangle  using System;     class Test {             // Function to find area      static float findArea(float a, float b,                          float c)      {                     // Length of sides must be positive          // and sum of any two sides          // must be smaller than third side.          if (a < 0 || b < 0 || c <0 ||           (a + b <= c) || a + c <=b ||               b + c <=a)          {              Console.Write("Not a valid triangle");              System.Environment.Exit(0);          }          float s = (a + b + c) / 2;          return (float)Math.Sqrt(s * (s - a) *                               (s - b) * (s - c));      }                 // Driver code      public static void Main()       {          float a = 3.0f;          float b = 4.0f;          float c = 5.0f;                 Console.Write("Area is " + findArea(a, b, c));      }  }     // This code is contributed Nitin Mittal.

## PHP

 

Output :

Area is 6

Finding area using coordinates:

If we are given coordinates of three corners, we can apply below Shoelace formula for area.

Area = | 1/2 [ (x1y2 + x2y3 + ... + xn-1yn + xny1) -
(x2y1 + x3y2 + ... + xnyn-1 + x1yn) ] |



## C++

 // C++ program to evaluate area of a polygon using  // shoelace formula  #include  using namespace std;      // (X[i], Y[i]) are coordinates of i'th point.  double polygonArea(double X[], double Y[], int n)  {      // Initialize area      double area = 0.0;          // Calculate value of shoelace formula      int j = n - 1;      for (int i = 0; i < n; i++)      {          area += (X[j] + X[i]) * (Y[j] - Y[i]);          j = i;  // j is previous vertex to i      }          // Return absolute value      return abs(area / 2.0);  }      // Driver program to test above function  int main()  {      double X[] = {0, 2, 4};      double Y[] = {1, 3, 7};          int n = sizeof(X)/sizeof(X);          cout << polygonArea(X, Y, n);  }

## Java

 // Java program to evaluate area of   // a polygon usingshoelace formula  import java.io.*;  import java.math.*;     class GFG {         // (X[i], Y[i]) are coordinates of i'th point.      static double polygonArea(double X[], double Y[], int n)      {          // Initialize area          double area = 0.0;                 // Calculate value of shoelace formula          int j = n - 1;          for (int i = 0; i < n; i++)          {              area += (X[j] + X[i]) * (Y[j] - Y[i]);                             // j is previous vertex to i              j = i;           }                 // Return absolute value          return Math.abs(area / 2.0);      }             // Driver program       public static void main (String[] args)       {          double X[] = {0, 2, 4};          double Y[] = {1, 3, 7};             int n = X.length;          System.out.println(polygonArea(X, Y, n));      }  }        // This code is contributed  // by Nikita Tiwari.

## Python3

 # Python 3 program to evaluate  # area of a polygon using  # shoelace formula     # (X[i], Y[i]) are coordinates of i'th point.  def polygonArea(X,Y, n) :         # Initialize area      area = 0.0          # Calculate value of shoelace formula      j = n - 1     for i in range( 0, n) :          area = area + (X[j] + X[i]) * (Y[j] - Y[i])          j = i  # j is previous vertex to i                    # Return absolute value      return abs(area // 2.0)          # Driver program to test above function  X = [0, 2, 4]  Y = [1, 3, 7]     n = len(X)  print(polygonArea(X, Y, n))        # This code is contributed  # by Nikita Tiwari.

## C#

 // C# program to evaluate area of   // a polygon usingshoelace formula  using System;     class GFG {         // (X[i], Y[i]) are coordinates       // of i'th point.      static double polygonArea(double []X,                         double []Y, int n)      {          // Initialize area          double area = 0.0;                 // Calculate value of shoelace          // formula          int j = n - 1;          for (int i = 0; i < n; i++)          {              area += (X[j] + X[i]) *                           (Y[j] - Y[i]);                             // j is previous vertex to i              j = i;           }                 // Return absolute value          return Math.Abs(area / 2.0);      }             // Driver program       public static void Main ()       {          double []X = {0, 2, 4};          double []Y = {1, 3, 7};             int n = X.Length;          Console.WriteLine(                   polygonArea(X, Y, n));      }  }     // This code is contributed by anuj_67.

## PHP

 

Output :

2

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