Area of largest Circle inscribe in N-sided Regular polygon in C Program?

Here we will see how to get the area of the circle which is inscribed in N-sided regular polygon. The N (number of sides) are given, and each side of the polygon is ‘a’

The approach is simple. One N sided polygon can be divided into N equal triangles, the whole angle for each triangle in center is 360/N, so −


#include <iostream>
#include <cmath>
using namespace std;
float area(float n, float a) {
   if (n < 0 || a < 0 ) //if the valuse are negative it is invalid
      return -1;
   float r = a/(2.0*tan((180/n) * 3.14159/180));
   float area = 3.14159 * r*r;
   return area;
int main() {
   float n = 8, a = 4;
   cout << "Area : " << area(n, a);


Area : 73.2422

Updated on: 20-Aug-2019


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