Area of circle inscribed within rhombus in C Program?

Here we will see the area of circle which is inscribed in a rhombus. The diagonals of the rhombus are ‘a’ and ‘b’. The radius of the circle is h.

Two diagonals are creating four equal triangles. Each triangle is right-angled triangle, so their area is −

Each side of the rhombus is the hypotenuses −

So the area of the circle is −

Example

#include <iostream>
#include <cmath>
using namespace std;
float area(float a, float b) {
   if (a < 0 || b < 0) //if the values are negative it is invalid
      return -1;
   float area = (3.1415 * (a*b * a*b))/(4 * (a*a + b*b));
   return area;
}
int main() {
   float a = 8, b= 10;
   cout << "Area is: " << area(a, b);
}

Output

Area is: 30.6488