UVA 10432 - Polygon Inside A Circle solution

problem link-click here

its a very easy problem just use  the formula of finding area of a polygon & the formula is

see the  above mentioned formulas in the picture ( collected from mathworlds.com )

Area = n*r*r/2 * sin ( 360/n)

here we go,


#include<bits/stdc++.h>
#define pi acos(-1)
using namespace std;

int main()
{
    double a,b,c;

    while(scanf("%lf%lf",&a,&b)==2)
    {
        c=((b*a*a)/2)*sin(2*pi/b);
        printf("%.3lf\n",c);
    }

    return 0;

}